[media] rc: protocol is not set on register for raw IR devices

ir_raw_event_register() sets up change_protocol(), and without that set,
rc_setup_rx_device() does not set the protocol for the device on register.

The standard udev rules run ir-keytable, which writes to the protocols
file again, which hides this problem.

Fixes: 7ff2c2bc ("[media] rc-main: split setup and unregister functions")

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>