dt-bindings: mmc: fsl-imx-esdhc: add i.MX8MP compatible string

Add compatible string for imx8mp
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1578893602-14395-2-git-send-email-Anson.Huang@nxp.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt

@@ -21,6 +21,7 @@ Required properties:
 	       "fsl,imx8mq-usdhc"
 	       "fsl,imx8mm-usdhc"
 	       "fsl,imx8mn-usdhc"
+	       "fsl,imx8mp-usdhc"
 	       "fsl,imx8qxp-usdhc"
 
 Optional properties: