[media] OMAP3: ISP: Add regulator control for omap34xx

The current omap3isp driver is missing regulator handling
for CSIb complex in omap34xx based devices. This patch
adds a mechanism for this to the omap3isp driver.

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>