ALSA: cmipci: Restore aux vol on suspend/resume

Save and restore CM_REG_AUX_VOL instead of register 0x24 twice on
suspend/resume.

Tested on CMI8738LX.

Fixes: cb60e5f5

 ("[ALSA] cmipci - Add PM support")
Signed-off-by: Jonathan Teh <jonathan.teh@outlook.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/DBAPR04MB7366CB3EA9C8521C35C56E8B920E9@DBAPR04MB7366.eurprd04.prod.outlook.com


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