ALSA: hda: More constifications

Apply const prefix to the remaining possible places: the string
tables, the rate tables, the verb tables, the index tables, etc.

Just for minor optimization and no functional changes.

Link: https://lore.kernel.org/r/20200105144823.29547-10-tiwai@suse.de


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