bindings: fsl-imx-sdma: Document fsl,imx8mq-sdma compatbile string

Add imx8mq sdma support.
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt

@@ -9,6 +9,7 @@ Required properties:
       "fsl,imx53-sdma"
       "fsl,imx6q-sdma"
       "fsl,imx7d-sdma"
+      "fsl,imx8mq-sdma"
   The -to variants should be preferred since they allow to determine the
   correct ROM script addresses needed for the driver to work without additional
   firmware.