arm: mx6: cm_fx6: add ethernet support

Add ethernet support for Compulab CM-FX6 CoM

Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>