ARM: dts: sun5i: add spi2 on A10s Olinuxino Micro

spi2 is available on the UEXT connector

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
[Maxime: Fixed the node order]
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>