Constifying "struct snd_soc_ops" moves some data to a read-only section, so
increase overall security.

This structure is also part of scripts/const_structs.checkpatch.

As an example, on a x86_64, with allmodconfig:
Before:
   text	   data	    bss	    dec	    hex	filename
   6315	   3696	      0	  10011	   271b	sound/soc/intel/boards/ehl_rt5660.o

After:
   text	   data	    bss	    dec	    hex	filename
   6379	   3648	      0	  10027	   272b	sound/soc/intel/boards/ehl_rt5660.o
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://msgid.link/r/2f0613bf4c6018569cdaac876d0589e49cf38a80.1715622793.git.christophe.jaillet@wanadoo.frSigned-off-by: Mark Brown <broonie@kernel.org>