[media] omap3isp: ccdc: Use generic frame sync event instead of private HS_VS event

The ccdc block in the omap3isp produces events whenever it starts receiving
a new frame. A private HS_VS event was used for this previously. Now, the
generic V4L2_EVENT_FRAME_SYNC event is being used for the purpose.

This patch also provides the frame sequence number to user space.

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