Add initial Toradex Colibri VF61 board support. Ethernet, UART
and SDHC cards are working. Cache latencies need to be a bit
higher than vf610.dtsi suggests. Those values are validated
by running multiple memory tests.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>