ARM: dts: imx7: Correct CPU supply name

i.MX7 uses cpufreq-dt driver which requires the CPU supply name to be
either "cpu0-supply" or "cpu-supply", correct it.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7-tqma7.dtsi

@@ -16,7 +16,7 @@ memory@80000000 {
 };
 
 &cpu0 {
-	arm-supply = <&sw1a_reg>;
+	cpu-supply = <&sw1a_reg>;
 };
 
 &i2c1 {

arch/arm/boot/dts/imx7d-zii-rmu2.dts

@@ -33,7 +33,7 @@ debug {
 };
 
 &cpu0 {
-	arm-supply = <&sw1a_reg>;
+	cpu-supply = <&sw1a_reg>;
 };
 
 &ecspi1 {

arch/arm/boot/dts/imx7d-zii-rpu2.dts

@@ -182,7 +182,7 @@ &adc2 {
 };
 
 &cpu0 {
-	arm-supply = <&sw1a_reg>;
+	cpu-supply = <&sw1a_reg>;
 };
 
 &clks {