[ALSA] ac97 - fix various issues with AD1986/AD1986A support

[ALSA] ac97 - fix various issues with AD1986/AD1986A support

Previously, ac97_codec.c was coded to support AD1986 and AD1986A
CODECs using code written for the AD1985 CODEC.  This allowed the
LINE_OUT and HEADPHONE jacks to function properly, however register
differences between the CODECs prevented line and microphone inputs
from functioning.
Specifically, this patch fixes issues with the following mixer
controls:  'V_REFOUT', 'Spread Front to Surround and Center/LFE',
'Exchange Front/Surround', 'Surround Jack Mode', and 'Channel Mode'.
This patch removes the undocumented AD1888 control
'High Pass Filter Enable' and adds the new control
'Exchange Mic/Line In'.

Signed-off-by: Randy Cushman <rcushman_linux@earthlink.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>