Let's just enable the module when we start using it (at stream on)
and benefit from runtime pm instead of enabling it at first open.

Also reorder the call to v4l2_pipeline_pm_get.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>