media: sun6i-csi: Use runtime pm for clocks and reset

Wrap the clock and reset preparation into runtime pm functions
for better organization of the code. Also fix the clock and
reset enable order to first deassert reset, as recommended in
Allwinner literature.

Make the driver depend on PM while at it since runtime pm is
mandatory for the driver to work.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>