dt-bindings: arm: fsl: Add bindings for SolidRun i.MX8MP SoM and boards

dt-bindings: arm: fsl: Add bindings for SolidRun i.MX8MP SoM and boards

Add bindings for SolidRun i.MX8M Plus System on Module based boards:

- CuBox-M is a complete produc with enclosure including the SoM
- HummingBoard Mate/Pro/Pulse/Ripple are evaluation boards with common
  design but different available interfaces.

Signed-off-by: Josua Mayer <josua@solid-run.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>