ALSA: ice17xx: Constify snd_ice1712_card_info

The snd_ice1712_card_info objects are referred only as read-only.
Let's make them const for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-49-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>