Add initial support for cm-fx6 module.

cm-fx6 is a module based on mx6q SoC with the following features:
- Up to 4GB of DDR3
- 1 LCD/DVI output port
- 1 HDMI output port
- 2 LVDS LCD ports
- Gigabit Ethernet
- Analog Audio
- CAN
- SATA
- NAND
- PCIE

This patch allows to boot up the module, configures the serial console,
the Ethernet adapter and the heartbeat led.

cm-fx6 is embedded inside the Utilite computer.
Signed-off-by: Valentin Raevsky <valentin@compulab.co.il>
Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>