ARM: dts: imx: Adjust CPU nodes

Make CPU nodes consistent throughout the i.MX dts files, which
also matches the description from ePAPR spec.

This also fixes the following W=1 warning in some cases:

Warning (unit_address_vs_reg): Node /cpus/cpu@0 has a unit name, but no reg property

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx1.dtsi

@@ -43,8 +43,9 @@
 		#size-cells = <0>;
 		#address-cells = <1>;
 
-		cpu: cpu@0 {
+		cpu@0 {
 			device_type = "cpu";
+			reg = <0>;
 			compatible = "arm,arm920t";
 			operating-points = <200000 1900000>;
 			clock-latency = <62500>;