arm64: dts: imx8mq-librem5-devkit: Use 0.9V for VDD_GPU

According to the imx8mq data sheet running VDD_GPU at 0.9V is enough
when not overclocking to 1GHz (which we currently don't do).
Signed-off-by: Guido Günther <guido.gunther@puri.sm>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts

@@ -318,7 +318,7 @@ buck3_reg: BUCK3 {
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1300000>;
 				regulator-boot-on;
-				rohm,dvs-run-voltage = <1000000>;
+				rohm,dvs-run-voltage = <900000>;
 			};
 
 			buck4_reg: BUCK4 {