sun7i: Add bananapi board

The Banana Pi is an A20 based development board using Raspberry Pi compatible
IO headers. It comes with 1 GB RAM, 1 Gb ethernet, 2x USB host, sata, hdmi
and stereo audio out + various expansion headers:

http://www.lemaker.org/

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