ARM: dts: imx25: Fix memory node duplication

Boards based on imx25 have duplicate memory nodes:

- One coming from the board dts file: memory@

- One coming from the imx25.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>
diff --git a/arch/arm/boot/dts/imx25-karo-tx25.dts b/arch/arm/boot/dts/imx25-karo-tx25.dts
index 5cb6967..f37e9a7 100644
--- a/arch/arm/boot/dts/imx25-karo-tx25.dts
+++ b/arch/arm/boot/dts/imx25-karo-tx25.dts
@@ -37,6 +37,7 @@
 	};
 
 	memory@80000000 {
+		device_type = "memory";
 		reg = <0x80000000 0x02000000 0x90000000 0x02000000>;
 	};
 };