ARM: dts: sun5i: Add dts file for the Empire Electronix D709 tablet

The Empire Electronix D709 tablet is a fairly standard 7" A13 tablet,
featuring usb-wifi, a micro-sd slot, micro-usb otg and headphone jack.

Empire Electronix is written on the back of the tablet, the D709 model
info can be found in the about tablet menu in android.

The PCB has no markings to speak of.

This dts file does not add support for the ft5x touchscreen found at
i2c bus 1, addr 0x38, irq PG11, because it does not work out of the box.
It seems it has been flashed with the wrong firmware and needs to have
alternative firmware uploaded at boot to make the touchscreen work
properly, when hot-booting from android into an upstream kernel the
touchscreen does work.

The Memsic MXC622X accelerometer at i2c bus 1, addr 0x15 also is not
enabled as there is no driver for it.

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