arm: mvebu: helios4: Enable mvebu GPIO

Make use of U-Boot's GPIO DM to control native GPIO and I2C IO expander.

Signed-off-by: Aditya Prayoga <aditya@kobol.io>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-By: Dennis Gilmore <dgilmore@redhat.com>
Reviewed-By: Dennis Gilmore <dgilmore@redhat.com>
Signed-off-by: Stefan Roese <sr@denx.de>