[ALSA] WM9712 fixes for ac97_patch.c

This patch by Luke Zhang fixes a couple of issues with the WM9712
support in ac97_patch.c
Changes:-
 o Fix Out3 ZC switch invert.
 o Extend capture volume control to 6 bits.
 o Change Mic 1 volume mask to 5 bits (31).
 o Add Mic 2 volume.

Signed-off-by: Luke Zhang <lzhang@intrinsyc.com>
Signed-off-by: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>