[media] media: soc-camera: use managed devm_regulator_bulk_get()

Using device-managed devm_regulator_bulk_get() eliminates the need to
release regulators explicitly.

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