[media] drx-j: Don't use buffer if an error occurs

[media] drx-j: Don't use buffer if an error occurs

drivers/media/dvb-frontends/drx39xyj/drxj.c: In function ‘drxj_dap_scu_atomic_read_reg16’:
drivers/media/dvb-frontends/drx39xyj/drxj.c:4170:9: warning: ‘*((void *)&buf+1)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  word = (u16) (buf[0] + (buf[1] << 8));
         ^
drivers/media/dvb-frontends/drx39xyj/drxj.c:4170:9: warning: ‘buf’ may be used uninitialized in this function [-Wmaybe-uninitialized]
drivers/media/dvb-frontends/drx39xyj/drxj.c: In function ‘drxj_dap_atomic_read_reg32.isra.59’:
drivers/media/dvb-frontends/drx39xyj/drxj.c:2186:7: warning: ‘*((void *)&buf+3)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  word = (u32) buf[3];
       ^
drivers/media/dvb-frontends/drx39xyj/drxj.c:2188:10: warning: ‘*((void *)&buf+2)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  word |= (u32) buf[2];
          ^
drivers/media/dvb-frontends/drx39xyj/drxj.c:2190:10: warning: ‘*((void *)&buf+1)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  word |= (u32) buf[1];
          ^
drivers/media/dvb-frontends/drx39xyj/drxj.c:2192:10: warning: ‘buf’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  word |= (u32) buf[0];
          ^

Acked-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>