[media] rc/streamzap: fix reporting response times

The streamzap driver has relatively low sampling resolution, and any
delays in reporting events seem to cause some minor problems for the
likes of irw when using the lirc bridge driver, resulting in a single
keypress registering as multiple independent ones, rather than as a
single press with repeats. If we call ir_raw_event_handle() more
frequently and reset the rawir kfifo at end-of-signal, the behavior
improves quite a bit.

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