ARM: dts: am57xx-idk-common: Hook smps12 regulator as cpu vdd-supply

am574x-idk has no cpu vdd-supply at the moment. Hence hook smps12
regulator as cpu vdd-supply in am57xx-idk-common as the same regulator
feeds on to cpu on am571/2/4-idks. So remove all the individual
instances and place that in common place.

Signed-off-by: Keerthy <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>

arch/arm/boot/dts/am571x-idk.dts

···
 	pinctrl-1 = <&mmc2_pins_hs>;
 	pinctrl-2 = <&mmc2_pins_ddr_rev20 &mmc2_iodelay_ddr_conf>;
 };
-
-&cpu0 {
-	vdd-supply = <&smps12_reg>;
-};

arch/arm/boot/dts/am572x-idk.dts

···
 	pinctrl-1 = <&mmc2_pins_hs>;
 	pinctrl-2 = <&mmc2_pins_ddr_rev20>;
 };
-
-&cpu0 {
-	vdd-supply = <&smps12_reg>;
-};

arch/arm/boot/dts/am57xx-idk-common.dtsi

···
 		};
 	};
 };
+
+&cpu0 {
+	vdd-supply = <&smps12_reg>;
+};