ARM: sun5i: dt: Add I2C controller nodes to the A10S dtsi

Allwinner A10S has 3 I2C controllers embedded on it. Add them to the
corresponding dtsi.

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