ARM: sun5i: dt: Add I2C muxings for sun5i A10S

The information has been extracted from the A10S-OLinuXino-Micro
schematics, as we do not have a user manual for A10S yet.

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>