uboot-imx

gpio: atmel_pio4: Move PIO4 definitions to head file

In order to make these PIO4 definitions shared with AT91 PIO4
pinctrl driver, move them from the existing gpio driver to the
head file, and rephrase them.

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