[media] media: au8522 change to create MC pad for ALSA Audio Out

Add new pad for ALSA Audio Out to au8522_media_pads.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>