dt-bindings: arm: imx: add imx8mm nitrogen support

The Nitrogen8M Mini is an ARM based single board computer (SBC).

Signed-off-by: Adrien Grassein <adrien.grassein@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -678,6 +678,7 @@ properties:
         items:
           - enum:
               - beacon,imx8mm-beacon-kit  # i.MX8MM Beacon Development Kit
+              - boundary,imx8mm-nitrogen8mm  # i.MX8MM Nitrogen Board
               - fsl,imx8mm-ddr4-evk       # i.MX8MM DDR4 EVK Board
               - fsl,imx8mm-evk            # i.MX8MM EVK Board
               - gw,imx8mm-gw71xx-0x       # i.MX8MM Gateworks Development Kit