The reference to snd_info_entry_ops is rather read-only, so declare it
as a const pointer. This allows a bit more optimization.
There should be no functional changes by this patch.
Link: https://lore.kernel.org/r/20200103081714.9560-29-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>