[media] serial_ir: ensure we're ready to receive interrupts

[media] serial_ir: ensure we're ready to receive interrupts

When the interrupt requested with devm_request_irq(), serial_ir.rcdev
is still null so will cause null deference if the irq handler is called
early on.

Also ensure that timeout_timer is setup.

Link: http://lkml.kernel.org/r/CA+55aFxsh2uF8gi5sN_guY3Z+tiLv7LpJYKBw+y8vqLzp+TsnQ@mail.gmail.com
[mchehab@s-opensource.com: moved serial_ir_probe() back to its original place]

Cc: <stable@vger.kernel.org> # 4.10
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>