[media] lirc: use refcounting for lirc devices

If a lirc device is unplugged, the struct rc_dev is freed even though
userspace can still have a file descriptor open on the lirc chardev. The
rc_dev structure can be used in a subsequent, or even currently executing
ioctl, read or write.

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