powerpc/85xx: Re-add the device_type soc to socrates.dts

The device_type "soc" is still required for MPC85xx boards.
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/boot/dts/socrates.dts

@@ -52,6 +52,7 @@ memory {
 	soc8544@e0000000 {
 		#address-cells = <1>;
 		#size-cells = <1>;
+		device_type = "soc";
 
 		ranges = <0x00000000 0xe0000000 0x00100000>;
 		reg = <0xe0000000 0x00001000>;	// CCSRBAR 1M