V4L/DVB: IR/mceusb: add tx callback functions and wire up

mchehab: merged with IR/mceusb: userspace buffer copy moved out of driver

    Userspace buffer copy moved out of driver and into lirc bridge driver

[mchehab@redhat.com: merged the patch to avoid compilation errors with allyesconfig ]
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>