[media] rc: rc-core: Add support for encode_wakeup drivers

[media] rc: rc-core: Add support for encode_wakeup drivers

Add support in rc-core for drivers which implement the wakeup scancode
filter by encoding the scancode using the raw IR encoders. This is by
way of rc_dev::encode_wakeup which should be set to true and
rc_dev::allowed_wakeup_protocols should be set to the raw IR encoders.

We also do not permit the mask to be set as we cannot generate IR
which would match that.

Signed-off-by: James Hogan <james@albanarts.com>
Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Cc: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>