ARM: dts: imx51: Fix memory node duplication

Boards based on imx51 have duplicate memory nodes:

- One coming from the board dts file: memory@

- One coming from the imx51.dtsi file.

Fix the duplication by removing the memory node from the dtsi file
and by adding 'device_type = "memory";' in the board dts.

Reported-by: Rob Herring <robh@kernel.org>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx51-apf51.dts

@@ -22,6 +22,7 @@
 	compatible = "armadeus,imx51-apf51", "fsl,imx51";
 
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0x20000000>;
 	};
 

arch/arm/boot/dts/imx51-babbage.dts

@@ -15,6 +15,7 @@
 	};
 
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0x20000000>;
 	};
 

arch/arm/boot/dts/imx51-digi-connectcore-som.dtsi

@@ -17,6 +17,7 @@
 	compatible = "digi,connectcore-ccxmx51-som", "fsl,imx51";
 
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0x08000000>;
 	};
 };

arch/arm/boot/dts/imx51-eukrea-cpuimx51.dtsi

@@ -23,6 +23,7 @@
 	compatible = "eukrea,cpuimx51", "fsl,imx51";
 
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0x10000000>; /* 256M */
 	};
 };

arch/arm/boot/dts/imx51-ts4800.dts

@@ -18,6 +18,7 @@
 	};
 
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0x10000000>;
 	};
 

arch/arm/boot/dts/imx51-zii-rdu1.dts

@@ -53,6 +53,7 @@
 
 	/* Will be filled by the bootloader */
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0>;
 	};
 

arch/arm/boot/dts/imx51-zii-scu2-mezz.dts

@@ -18,6 +18,7 @@
 
 	/* Will be filled by the bootloader */
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0>;
 	};
 

arch/arm/boot/dts/imx51-zii-scu3-esb.dts

@@ -18,6 +18,7 @@
 
 	/* Will be filled by the bootloader */
 	memory@90000000 {
+		device_type = "memory";
 		reg = <0x90000000 0>;
 	};
 

arch/arm/boot/dts/imx51.dtsi

@@ -16,10 +16,8 @@
 	 * The decompressor and also some bootloaders rely on a
 	 * pre-existing /chosen node to be available to insert the
 	 * command line and merge other ATAGS info.
-	 * Also for U-Boot there must be a pre-existing /memory node.
 	 */
 	chosen {};
-	memory { device_type = "memory"; };
 
 	aliases {
 		ethernet0 = &fec;