ARM: sun7i: add support for A20-OLinuXino-Lime2

This adds support for the Olimex A20-OLinuXino-Lime2
https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXIno-LIME2



Differences to previous Lime boards are 1GB RAM and gigabit ethernet

Signed-off-by: Iain Paton <ipaton0@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>