[media] adv7604: improve log_status for HDMI/DVI-D signals

Don't log if there is no signal.
If there is a signal, then also log HDCP and audio status.

Signed-off-by: Mats Randgaard <matrandg@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>