sunxi: Move all boards to the driver-model

Now that we've everything prepared for it remove the DM settings from the
defconfig(s) and simply always set them for sunxi.

This makes all sunxi boards allways use the driver model for gpios and
ethernet, and allows us to move over more bits to the driver-model without
the need to introduce #ifdef-ery for boards which are not yet using DM.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Ian Campbell <ijc@hellion.org.uk>