[media] adv7604: add hdmi driver strength adjustment

The driver strength is board dependent, so set it from the platform_data.

Signed-off-by: Mikhail Khelik <mkhelik@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>