ARM: dts: sun5i: Add mmc1 / sdio-wifi node to mk802

The a10s mk802 uses a rtl8189es sdio wifi chip, add a node enabling
the mmc1 controller, this enables using the wifi chip (together with
an out of tree sdio driver for it).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>