[media] OMAP3: RX-51: define vdds_csib regulator supply

The RX-51 uses the CSIb IO complex for camera operation. The
board file is missing definition for the regulator supplying
the CSIb complex, so this is added for better power
management.

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