[media] rc: Postpone ISR registration

An early registration of an ISR was causing a crash to several users (for
example, with the ite-cir driver: http://bugs.launchpad.net/bugs/972723

).
The reason was that IRQs were being triggered before a driver
initialisation was completed.

This patch fixes this by moving the invocation to request_irq() and to
request_region() to a later stage on the driver probe function.

Cc: <stable@vger.kernel.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>