[media] rc-core: improve the lirc protocol reporting

Commit 275ddb40 removed the lirc
"protocol" but kept backwards compatibility by always listing
the protocol as present and enabled. This patch further improves
the logic by only listing the protocol if the lirc module is loaded
(or if lirc is builtin).

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>