[media] s2255drv: atomic submit urb in completion handler

An usb_submit_urb should be atomic in a completion handler. This fixes
"BUG: scheduling while atomic" messages.

Signed-off-by: Pete Eberlein <pete@sensoray.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>