ARM: dts: bcm281xx: Add i2c busses

Add the DTS nodes for all the i2c busses in the SoC.

Signed-off-by: Tim Kryger <tim.kryger@linaro.org>
Reviewed-by: Christian Daudt <csd@broadcom.com>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Signed-off-by: Christian Daudt <bcm@fixthebug.org>