dt-bindings: arm: Add Gateworks i.MX8M Plus gw71xx-2x board

Add DT compatible string for a Gateworks GW71xx-2x board based on
the i.MX8M Plus SoC from NXP.
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -1032,6 +1032,7 @@ properties:
               - beacon,imx8mp-beacon-kit  # i.MX8MP Beacon Development Kit
               - dmo,imx8mp-data-modul-edm-sbc # i.MX8MP eDM SBC
               - fsl,imx8mp-evk            # i.MX8MP EVK Board
+              - gateworks,imx8mp-gw71xx-2x # i.MX8MP Gateworks Board
               - gateworks,imx8mp-gw74xx   # i.MX8MP Gateworks Board
               - gateworks,imx8mp-gw7905-2x # i.MX8MP Gateworks Board
               - polyhex,imx8mp-debix      # Polyhex Debix boards