V4L/DVB: IR: add ir-core to lirc userspace decoder bridge driver

v2: copy of buffer data from userspace done inside this plugin/driver,
keeping the actual drivers minimal, and more flexible in what we can
deliver to them later on (they may be fed from within kernelspace later
on, by an in-kernel IR encoder).

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>