[media] dvb_usb_v2: suspend/resume stop/start USB streaming

Stop remote polling and USB streaming before suspend and resume
those when back to normal operation.

It is far away from complete implementation, but at least it does
not hang system anymore on suspend while streaming is ongoing.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>