ALSA: intel8x0: More constifications

Apply const prefix to more places: the static tables for PCM
definitions, the register tables, etc.

Just for minor optimization and no functional changes.

Link: https://lore.kernel.org/r/20200105144823.29547-9-tiwai@suse.de


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