arm64: dts: rockchip: update opp-table for rk3308

Analysis the data of different leakage, if the frequency is 1.2G,
then the voltage must be 1200mV.

Change-Id: I5160cf2ec7bab48172f549b138881656b9538cd3
Signed-off-by: shengfei Xu <xsf@rock-chips.com>

Author: power-xsf

arch/arm64/boot/dts/rockchip/rk3308.dtsi

@@ -103,7 +103,7 @@
 		};
 		opp-1200000000 {
 			opp-hz = /bits/ 64 <1200000000>;
-			opp-microvolt = <1175000 1175000 1340000>;
+			opp-microvolt = <1200000 1200000 1340000>;
 			clock-latency-ns = <40000>;
 		};
 	};