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 <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

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

···
 };
 
 &cpu0 {
-	arm-supply = <&sw1a_reg>;
+	cpu-supply = <&sw1a_reg>;
 };
 
 &i2c1 {

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

···
 };
 
 &cpu0 {
-	arm-supply = <&sw1a_reg>;
+	cpu-supply = <&sw1a_reg>;
 };
 
 &ecspi1 {

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

···
 };
 
 &cpu0 {
-	arm-supply = <&sw1a_reg>;
+	cpu-supply = <&sw1a_reg>;
 };
 
 &clks {