sunxi: Add inet98v_rev2 defconfig and dts file

The inet98v_rev2 is a pcb used in generic A13 based tablets. It features
volume buttons, a power barrel, micro-usb otg, headphone connector and
a power button.

The dts file is identical to the one submitted to the upstream kernel.

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