dt-bindings: arm: Document i.MX8QXP AI_ML board binding

Document devicetree binding of i.MX8QXP AI_ML board from Einfochips.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -225,6 +225,7 @@ properties:
       - description: i.MX8QXP based Boards
         items:
           - enum:
+              - einfochips,imx8qxp-ai_ml  # i.MX8QXP AI_ML Board
               - fsl,imx8qxp-mek           # i.MX8QXP MEK Board
           - const: fsl,imx8qxp