pinctrl: sunxi: Add of_xlate function

Since the pin controller of sunxi chips is represented as a single bank
in the driver.
Since this is neither convenient nor represented that way in the
datasheets, define a custom of_xlate function with the layout <bank pin
flag>

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
sunxi: dts: Report the pinctrl nodes as gpio-controllers

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
sunxi: a13-olinuxino: Add user LED to the device tree

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>