This adds a small backlight layer. It provides a backlight device
on which the brightness parameter can be used to adjust the brightness.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

This IP is present on the at91sam9 until the sam9g45, on the sam9x5 we use a
new IP.

This driver is based on the linux one.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>