mac80211: fix kconf build warnings

mac80211: fix kconf build warnings

This patch cleans up the following warnings during build:

"warning: format not a string literal"

```
conf.c: In function 'conf_askvalue':
conf.c:89:17: warning: format not a string literal and no format arguments [-Wformat-security]
    89 |                 printf(_("(NEW) "));
      |                 ^~~~~~
conf.c: In function 'conf_choice':
conf.c:285:33: warning: format not a string literal and no format arguments [-Wformat-security]
  285 |                                 printf(_(" (NEW)"));
      |                                 ^~~~~~
conf.c: In function 'check_conf':
conf.c:440:41: warning: format not a string literal and no format arguments [-Wformat-security]
  440 |                                         printf(_("*\n* Restart config...\n*\n"));
      |                                         ^~~~~~
conf.c: In function 'main':
conf.c:617:41: warning: format not a string literal and no format arguments [-Wformat-security]
  617 |                                         _("\n*** The configuration requires explicit update.\n\n"));
      |                                         ^
conf.c:669:25: warning: format not a string literal and no format arguments [-Wformat-security]
  669 |                         fprintf(stderr, _("\n*** Error during writing of the configuration.\n\n"));
      |                         ^~~~~~~
conf.c:673:25: warning: format not a string literal and no format arguments [-Wformat-security]
  673 |                         fprintf(stderr, _("\n*** Error during update of the configuration.\n\n"));
      |                         ^~~~~~~
conf.c:684:25: warning: format not a string literal and no format arguments [-Wformat-security]
  684 |                         fprintf(stderr, _("\n*** Error during writing of the configuration.\n\n"));
      |                         ^~~~~~~
```

And POSIX Yacc warnings
```
lex -ozconf.lex.c -L zconf.l
yacc -ozconf.tab.c -t -l zconf.y
zconf.y:34.1-7: warning: POSIX Yacc does not support %expect [-Wyacc]
    34 | %expect 32
      | ^~~~~~~
zconf.y:97.1-11: warning: POSIX Yacc does not support %destructor [-Wyacc]
    97 | %destructor {
      | ^~~~~~~~~~~
gcc -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -DKBUILD_NO_NLS   -c -o zconf.tab.o zconf.tab.c
gcc   conf.o zconf.tab.o   -o conf
```

After:

gcc -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -DKBUILD_NO_NLS   -c -o conf.o conf.c
yacc -Wno-yacc -ozconf.tab.c -t -l zconf.y
gcc -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer -DKBUILD_NO_NLS   -c -o zconf.tab.o zconf.tab.c
gcc   conf.o zconf.tab.o   -o conf

Signed-off-by: Sean Khan <datapronix@protonmail.com>
Link: https://github.com/openwrt/openwrt/pull/15953
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>