ALSA: pci: Constify snd_pci_quirk tables

The snd_pci_quirk tables are referred as read-only, hence they can be
declared as const gracefully.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-59-tiwai@suse.de


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