ARM: dts: add iomuxc-gpr device node for imx6sl

Add iomuxc gpr device node for imx6sl.
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6sl.dtsi

@@ -528,6 +528,11 @@ gpc: gpc@020dc000 {
 				interrupts = <0 89 0x04>;
 			};
 
+			gpr: iomuxc-gpr@020e0000 {
+				compatible = "fsl,imx6sl-iomuxc-gpr", "syscon";
+				reg = <0x020e0000 0x38>;
+			};
+
 			iomuxc: iomuxc@020e0000 {
 				compatible = "fsl,imx6sl-iomuxc";
 				reg = <0x020e0000 0x4000>;