dt-bindings: fsl-quadspi: Add the example of two SPI NOR

Improve the bindings example by adding an example of how to represent
two SPI NOR devices.
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>
Acked-by: NHan Xu <han.xu@nxp.com>
Signed-off-by: NCyrille Pitchen <cyrille.pitchen@wedev4u.fr>
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>

Documentation/devicetree/bindings/mtd/fsl-quadspi.txt

@@ -39,3 +39,27 @@ qspi0: quadspi@40044000 {
 		....
 	};
 };
+
+Example showing the usage of two SPI NOR devices:
+
+&qspi2 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_qspi2>;
+	status = "okay";
+
+	flash0: n25q256a@0 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "micron,n25q256a", "jedec,spi-nor";
+		spi-max-frequency = <29000000>;
+		reg = <0>;
+	};
+
+	flash1: n25q256a@1 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "micron,n25q256a", "jedec,spi-nor";
+		spi-max-frequency = <29000000>;
+		reg = <1>;
+	};
+};