[media] fsl-viu: convert to the control framework

Interestingly enough, the existing control handling code basically did
nothing. At least the new code will inherit the controls from the
saa7115 driver.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>