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.