dt-bindings: fsl: add imx7ulp system integration module binding

Add i.MX7ULP system integration module (SIM) binding.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/freescale/fsl,imx7ulp-sim.txt

+Freescale i.MX7ULP System Integration Module
+----------------------------------------------
+The system integration module (SIM) provides system control and chip configuration
+registers. In this module, chip revision information is located in JTAG ID register,
+and a set of registers have been made available in DGO domain for SW use, with the
+objective to maintain its value between system resets.
+
+Required properties:
+- compatible:	Should be "fsl,imx7ulp-sim".
+- reg:		Specifies base physical address and size of the register sets.
+
+Example:
+sim: sim@410a3000 {
+	compatible = "fsl,imx7ulp-sim", "syscon";
+	reg = <0x410a3000 0x1000>;
+};