kernel: ltq-deu: fix compilation warning

kernel: ltq-deu: fix compilation warning

Fix compilation warning for fallthrough and unused variables.
Fix compilation warning:
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_des.c: In function 'ifx_deu_des':
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_des.c:206:35: error: this statement may fall through [-Werror=implicit-fallthrough=]
  206 |                         des->K3LR = DEU_ENDIAN_SWAP(*((u32 *) key + 5));
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_des.c:209:17: note: here
  209 |                 case 16:
      |                 ^~~~
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_des.c:211:35: error: this statement may fall through [-Werror=implicit-fallthrough=]
  211 |                         des->K2LR = DEU_ENDIAN_SWAP(*((u32 *) key + 3));
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_des.c:214:17: note: here
  214 |                 case 8:
      |                 ^~~~
cc1: all warnings being treated as errors

/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_aes.c: In function 'ifx_deu_aes':
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_aes.c:260:21: error: unused variable 'ctx' [-Werror=unused-variable]
  260 |     struct aes_ctx *ctx = (struct aes_ctx *)ctx_arg;
      |                     ^~~
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_aes.c: In function 'ifx_deu_aes_xts':
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_aes.c:702:21: error: unused variable 'ctx' [-Werror=unused-variable]
  702 |     struct aes_ctx *ctx = (struct aes_ctx *)ctx_arg;
      |                     ^~~
cc1: all warnings being treated as errors

/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_sha1.c: In function 'sha1_final':
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_sha1.c:203:19: error: unused variable 'flag' [-Werror=unused-variable]
  203 |     unsigned long flag;
      |                   ^~~~
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_sha1.c:202:33: error: unused variable 'hashs' [-Werror=unused-variable]
  202 |     volatile struct deu_hash_t *hashs = (struct deu_hash_t *) HASH_START;
      |                                 ^~~~~
cc1: all warnings being treated as errors

/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_md5.c: In function 'md5_init':
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_md5.c:146:33: error: unused variable 'hash' [-Werror=unused-variable]
  146 |     volatile struct deu_hash_t *hash = (struct deu_hash_t *) HASH_START;
      |                                 ^~~~
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_md5.c: In function 'md5_final':
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_md5.c:204:19: error: unused variable 'flag' [-Werror=unused-variable]
  204 |     unsigned long flag;
      |                   ^~~~
/home/ansuel/openwrt-ansuel/openwrt/build_dir/target-mips-openwrt-linux-musl_musl/linux-lantiq_xway/ltq-deu-danube/ltq-deu/ifxmips_md5.c:203:33: error: unused variable 'hashs' [-Werror=unused-variable]
  203 |     volatile struct deu_hash_t *hashs = (struct deu_hash_t *) HASH_START;
      |                                 ^~~~~
cc1: all warnings being treated as errors

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>