[media] adp1653: Add driver for LED flash controller

This patch adds the driver for the adp1653 LED flash controller. This
controller supports a high power led in flash and torch modes and an
indicator light, sometimes also called privacy light.

The adp1653 is used on the Nokia N900.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Tuukka Toivonen <tuukkat76@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: David Cohen <dacohen@gmail.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>