ALSA: hda - Add helper functions to cache the current pinctl target

We already have the list of whole pin widgets and there is an unused
space in the list; let's use it for caching the current pinctl value.

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

diff --cc sound/pci/hda/hda_codec.c
Simple merge

diff --cc sound/pci/hda/hda_codec.h
Simple merge

diff --cc sound/pci/hda/hda_local.h
Simple merge