dt-bindings: fsl: scu: add new compatible string for ocotp

Add new compatible string "fsl,imx8qm-scu-ocotp" into binding
doc  for i.MX8 SCU OCOTP driver.
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20190818093345.29647-7-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt

@@ -136,7 +136,9 @@ Required properties:
 OCOTP bindings based on SCU Message Protocol
 ------------------------------------------------------------
 Required properties:
-- compatible:		Should be "fsl,imx8qxp-scu-ocotp"
+- compatible:		Should be one of:
+			"fsl,imx8qm-scu-ocotp",
+			"fsl,imx8qxp-scu-ocotp".
 - #address-cells:	Must be 1. Contains byte index
 - #size-cells:		Must be 1. Contains byte length