dt-bindings: riscv: microchip: document the aries m100pfsevp

Add a compatible for the Aries Embedded M100PFSEVP SOM + EVK platform.

Link: https://www.aries-embedded.com/polarfire-soc-fpga-microsemi-m100pfs-som-mpfs025t-pcie-serdes


Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>