[media] adv7604: driver for the Analog Devices ADV7604 video decoder

Initial version of this driver.

The full datasheets are available from the Analog Devices website:

  http://ez.analog.com/docs/DOC-1545



Not all features of the receiver are supported by this driver for various
reasons. Most notably:

- No CEC support (the CEC API needs a lot more discussion)
- Only port A of the four HDMI input ports is implemented (our hardware only
  uses that port)
- No HDCP repeater support (we don't use that either)

And since there are some 600-odd pages of datasheet for this single device,
I'm sure that there are many more things missing, but this driver does work
well for our hardware.

Note that I am using the register addresses instead of register names: the
datasheet containing the register descriptions is organized by register
address. Using names would make the datasheet lookup very hard. An attempt
was made to try and document what is being done when registers are used
instead.

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