[media] cec: adv7604: add cec support

Add CEC support to the adv7604 driver.

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
[k.debski@samsung.com: Merged changes from CEC Updates commit by Hans Verkuil]
[k.debski@samsung.com: add missing methods cec/io_write_and_or]
[k.debski@samsung.com: change adv7604 to adv76xx in added functions]
[hansverk@cisco.com: use _clr_set instead of _and_or]

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>