Add support for the Digi CCIMX6UL SBC Pro.
It is based on the Digi CCIMX6UL SOM with 256MB RAM and 256MB NAND
flash.

v2:
- fix includes
- rename folder to som
- switch to compressed dtb
- remove the unnecessary get_runtime_offset
all from Ahmad Fatoum

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>