[media] lirc_dev: remove unused set_use_inc/set_use_dec

Since there are no users of this functionality, it can be removed
altogether.

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