[media] V4L: pxa-camera: switch to using standard PM hooks

The pxa-camera driver doesn't need soc-camera specific PM callbacks,
switch it to using the standard PM hooks instead.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>