[media] rc: Fix double free in gpio_ir_recv_probe()

At the 'err_request_irq' label, rc_unregister_device(rcdev) frees its
argument. So when we fall through to the 'err_gpio_request' label
further down and call rc_free_device(rcdev) then that's a double free.
Fix that by moving 'rcdev = NULL' from after the call to
rc_free_device() to after rc_unregister_device(). That fixes the
problem since rc_free_device() just does nothing if passed NULL and
there's no further use of 'rcdev' after the call to rc_free_device()
so it's not needed there.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>