adv7604: Add adv7611 support

This patch adds support for the Analog Devices ADV7611 HDMI receiver.
The adv7611 is quite similar to the adv7604. It has only one instead of four
HDMI inputs and no analog frontend though. Also some register bits have been
shuffled around, but large parts of their register maps are compatible.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>