ALSA: cs46xx: constify snd_pcm_ops structures

ALSA: cs46xx: constify snd_pcm_ops structures

Declare snd_pcm_ops structures as const as they are either stored in the
ops field of a snd_pcm_substream structure or passed as an argument to
the function snd_pcm_set_ops. The function argument and the ops field
are of type const, so snd_pcm_ops structures having this property
can be made const too.

File size before: sound/pci/cs46xx/cs46xx_lib.o
   text	   data	    bss	    dec	    hex	filename
  26047	   5304	     16	  31367	   7a87	sound/pci/cs46xx/cs46xx_lib.o

File size after: sound/pci/cs46xx/cs46xx_lib.o
   text	   data	    bss	    dec	    hex	filename
  27335	   4036	     16	  31387	   7a9b	sound/pci/cs46xx/cs46xx_lib.o

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>