[media] rc: raw IR drivers cannot handle cec, unknown or other

unknown and other are for IR protocols for which we have no decoder,
so the raw IR drivers have no chance of generating them. cec is not
an IR protocol.

Signed-off-by: Sean Young <sean@mess.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>