dt-bindings: arm: fsl: Add the imx8mq boards

Add an entry for imx8mq based boards
Signed-off-by: Angus Ainslie (Purism) <angus@akkea.ca>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -178,6 +178,13 @@ properties:
               - fsl,imx8mm-evk            # i.MX8MM EVK Board
           - const: fsl,imx8mm
 
+      - description: i.MX8MQ based Boards
+        items:
+          - enum:
+              - fsl,imx8mq-evk            # i.MX8MQ EVK Board
+              - purism,librem5-devkit     # Purism Librem5 devkit
+          - const: fsl,imx8mq
+
       - description: i.MX8QXP based Boards
         items:
           - enum: