ARM: dts: stm32: Add Engicam MicroGEA STM32MP1 Micro SoM

MicroGEA STM32MP1 is a STM32MP157A based Micro SoM.

General features:
- STM32MP157AAC
- Up to 1GB DDR3L-800
- 512MB Nand flash
- I2S

MicroGEA STM32MP1 needs to mount on top of Engicam MicroDev carrier
boards for creating complete platform solutions.

Linux dts commit details:

commit <0be81dfaeaf8> ("ARM: dts: stm32: Add Engicam MicroGEA STM32MP1
SoM")

Add support for it.

Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>