[media] winbond-cir: add carrier detection

The winbond hardware has a counter for leading edges, which increases as
they are received. As we read raw IR from a fifo in an interrupt handler,
we cannot correlate them to specific IR pulses so we simply count all
pulses and edges until we go idle and disable the receiver.

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