[media] redrat3: errors on unplug

In an usb disconnect handler, the urbs have already been cancelled so the
attempt to disable the IR receiver just results in errors:
[  899.638862] redrat3 7-2:1.0: redrat3_send_cmd: Error sending rr3 cmd res -110, data 0
[  899.638870] redrat3 7-2:1.0: redrat3_disable_detector: detector status: 251, should be 0

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>