ARM: sun7i: Enable the I2C controllers

The Allwinner A20 shares the same I2C controller than the one that could
be found on earlier SoCs from Allwinner. There is only a few more of
these controllers. Add all of them in the DTSI.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
ARM: sun7i: Add the pin muxing options for the I2C controllers

The A20 boards we currently have share the same pins for the i2c
controllers they share. Add them to the DTSI.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
ARM: sun7i: cubieboard2: Enable the I2C controllers

The Cubieboard2 uses both the i2c0 and i2c1 controllers. Enable them in
the DT.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
ARM: sun7i: olinuxino-micro: Enable the I2C controllers

The A20-olinuxino-micro uses the first three I2C controllers found on
the A20. Enable them in the DT.

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