ARM: dts: TS-7970: add basic device tree

These device trees add support for TS-7970 by Technologic Systems.

More details here:
   https://wiki.embeddedarm.com/wiki/TS-7970



Signed-off-by: Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>