[media] media: au0828 Use au8522_media_pads enum for pad defines

Change au0828-core to use au8522_media_pads enum defines
instead of hard-coding the pad values.

[mchehab@osg.samsung.com: patch rebased, as the code was
 moved to au0828-video.c. Also added AU8522_PAD_INPUT to the list
 of pad number replacements]

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