[media] adv7180: Add support for the adv7280-m/adv7281-m/adv7281-ma/adv7282-m

This patch adds support for the adv7280-m/adv2781-m/adv7281-ma/adv7282-m
devices to the adv7180 driver. They are very similar to the
adv7280/adv7281/adv7282 but instead of parallel video out they feature a
MIPI CSI2 transmitter.

The CSI2 transmitter is configured via a separate I2C address, so we need to
register a dummy device for it.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Federico Vaga <federico.vaga@gmail.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>