media: cec: Respond to unregistered initiators, when applicable

Running CEC 1.4 compliance test we get the following error on test
11.1.6.2: "ERROR: The DUT did not broadcast a
<Report Physical Address> message to the unregistered device."

Fix this by letting GIVE_PHYSICAL_ADDR message respond to unregistered
device. Also, GIVE_DEVICE_VENDOR_ID and GIVE_FEATURES fall in the
same category so, respond also to these messages.

With this fix we pass CEC 1.4 official compliance.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Cc: Joao Pinto <jpinto@synopsys.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: <stable@vger.kernel.org>      # for v4.10 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>