media: rc: only register protocol for rc device if enabled

The raw_register function exists to create input devices associated with
that IR protocol.

If the mce_kbd module is loaded, then every rc device will have mce_kbd
input devices, even if the protocol is not enabled. Change this to call
the register function to when the protocol is enabled.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>