[media] omap3isp: Configure HS/VS interrupt source before enabling interrupts

This needs to be performed before enabling interrupts as the sensor
might be free-running and the ISP default setting (HS edge) would put an
unnecessary burden on the CPU.

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