dt-bindings: arm: fsl: add nxp based toradex colibri-imx7 bindings

Document the NXP SoC based Toradex Colibri iMX7S/D module
and the Aster carrier board devicetree bindings.

Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>