uboot-imx

gpio: atmel_pio4: Rework to support DM & DT

Rework the driver to support driver model and device tree, and
support to regard the pio4 pinctrl device as a child of
atmel_pio4 device.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>