[media] omap3isp: Configure CSI-2 phy based on platform data

Configure CSI-2 phy based on platform data in the ISP driver. For that, the
new V4L2_CID_IMAGE_SOURCE_PIXEL_RATE control is used. Previously the same
was configured from the board code.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>