ARM: dts: imx: Change gpmi nand node name to nand-controller

Change i.MX SoCs nand node name from "gpmi-nand" to "nand-controller" to
be compliant with yaml schema, it requires the nodename to be
"nand-controller".

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
diff --git a/arch/arm/boot/dts/imx6ul.dtsi b/arch/arm/boot/dts/imx6ul.dtsi
index 2b088f2..d7d9f3e 100644
--- a/arch/arm/boot/dts/imx6ul.dtsi
+++ b/arch/arm/boot/dts/imx6ul.dtsi
@@ -174,7 +174,7 @@ dma_apbh: dma-apbh@1804000 {
 			clocks = <&clks IMX6UL_CLK_APBHDMA>;
 		};
 
-		gpmi: gpmi-nand@1806000 {
+		gpmi: nand-controller@1806000 {
 			compatible = "fsl,imx6q-gpmi-nand";
 			#address-cells = <1>;
 			#size-cells = <1>;