arm: mx6: cm-fx6: change dtb node for ethaddr

When passing eth address to Linux via dtb, the "local-mac-address"
property should be set for "/soc/aips-bus@02100000/ethernet@02188000",
not "/fec".

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