ARM: dts: imx: Use flash@0,0 pattern

Per mtd-physmap.yaml, 'nor@0,0' is not a valid node pattern.

Change it to 'flash@0,0' to fix the following dt-schema warning:

imx1-ads.dtb: nor@0,0: $nodename:0: 'nor@0,0' does not match '^(flash|.*sram|nand)(@.*)?$'
	from schema $id: http://devicetree.org/schemas/mtd/mtd-physmap.yaml#Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/nxp/imx/imx1-ads.dts

@@ -65,7 +65,7 @@ &weim {
 	pinctrl-0 = <&pinctrl_weim>;
 	status = "okay";
 
-	nor: nor@0,0 {
+	nor: flash@0,0 {
 		compatible = "cfi-flash";
 		reg = <0 0x00000000 0x02000000>;
 		bank-width = <4>;

arch/arm/boot/dts/nxp/imx/imx1-apf9328.dts

@@ -45,7 +45,7 @@ &weim {
 	pinctrl-0 = <&pinctrl_weim>;
 	status = "okay";
 
-	nor: nor@0,0 {
+	nor: flash@0,0 {
 		compatible = "cfi-flash";
 		reg = <0 0x00000000 0x02000000>;
 		bank-width = <2>;

arch/arm/boot/dts/nxp/imx/imx27-eukrea-cpuimx27.dtsi

@@ -90,7 +90,7 @@ &usbotg {
 &weim {
 	status = "okay";
 
-	nor: nor@0,0 {
+	nor: flash@0,0 {
 		#address-cells = <1>;
 		#size-cells = <1>;
 		compatible = "cfi-flash";

arch/arm/boot/dts/nxp/imx/imx27-phytec-phycore-som.dtsi

@@ -314,7 +314,7 @@ &usbotg {
 &weim {
 	status = "okay";
 
-	nor: nor@0,0 {
+	nor: flash@0,0 {
 		compatible = "cfi-flash";
 		reg = <0 0x00000000 0x02000000>;
 		bank-width = <2>;