ARM: dts: colibri-imx6ull-emmc: add device tree

Add a device tree for a Colibri iMX6ULL 1GB which has a eMMC instead of
the raw NAND used on other SKUs.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>