media: venus: vdec: ensure venus is powered on during stream off

Video decoder driver auto-suspends the hardware if there is no
exchange of command or response for certain amount of time.
In auto suspended state, it becomes mandatory to power on the
hardware before requesting it to process a command. The fix
ensures the hardware is powered on during stop streaming.

Signed-off-by: Vikash Garodia <quic_vgarodia@quicinc.com>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>