ALSA: hda/ca0132 - Add ZxR 600 ohm gain control

This patch adds a control for 600 ohm gain on the Sound Blaster ZxR.

Signed-off-by: Connor McAdams <conmanx360@gmail.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>