dt-bindings: arm: fsl: add nxp based toradex colibri bindings

Document Colibri iMX6S/DL V1.1x re-design devicetree binding.

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>