[media] hdpvr: fix race conditon during start of streaming

status has to be set to STREAMING before the streaming worker is
queued. hdpvr_transmit_buffers() will exit immediately otherwise.

Reported-by: Joerg Desch <vvd.joede@googlemail.com>
CC: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>