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

On a x86_64, with allmodconfig:
Before:
   text	   data	    bss	    dec	    hex	filename
  44519	   2888	     48	  47455	   b95f	sound/soc/sof/topology.o

After:
   text	   data	    bss	    dec	    hex	filename
  44839	   2552	     48	  47439	   b94f	sound/soc/sof/topology.o
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://msgid.link/r/2d9f5b75e979eb38b6f3baf85dfa1f0fdb3447ef.1715526069.git.christophe.jaillet@wanadoo.frSigned-off-by: Mark Brown <broonie@kernel.org>