imx6: aristainetos: prepare dts for other board versions

as we switch to support DM and DTS, rework the existing
DTS trees. Change also Linux specific Device trees, goal
is to push this changes to linux.

Collect U-Boot specific changes in separate "*u-boot*" dts
files.

Signed-off-by: Heiko Schocher <hs@denx.de>
12 files changed