arm64: dts: zii-ultra: fix 12V_MAIN voltage

As this is a fixed regulator on the board there was no harm in the wrong
voltage being specified, apart from a confusing reporting to userspace.

Fixes: 4a13b3be ("arm64: dts: imx: add Zii Ultra board support")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-zii-ultra.dtsi

@@ -45,8 +45,8 @@ pcie1_refclk: clock-pcie1-refclk {
 	reg_12p0_main: regulator-12p0-main {
 		compatible = "regulator-fixed";
 		regulator-name = "12V_MAIN";
-		regulator-min-microvolt = <5000000>;
-		regulator-max-microvolt = <5000000>;
+		regulator-min-microvolt = <12000000>;
+		regulator-max-microvolt = <12000000>;
 		regulator-always-on;
 	};