ARM: dts: meson8: use the actual frequency for the GPU's 182.1MHz OPP

The clock setup on Meson8 cannot achieve a Mali frequency of exactly
182.15MHz. The vendor driver uses "FCLK_DIV7 / 2" for this frequency,
which translates to 2550MHz / 7 / 2 = 182142857Hz.
Update the GPU operating point to that specific frequency to not confuse
myself when comparing the frequency from the .dts with the actual clock
rate on the system.

Fixes: 7d3f6b53 ("ARM: dts: meson8: add the Mali-450 MP6 GPU")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

arch/arm/boot/dts/meson8.dtsi

@@ -130,8 +130,8 @@ opp-1992000000 {
 	gpu_opp_table: gpu-opp-table {
 		compatible = "operating-points-v2";
 
-		opp-182150000 {
-			opp-hz = /bits/ 64 <182150000>;
+		opp-182142857 {
+			opp-hz = /bits/ 64 <182142857>;
 			opp-microvolt = <1150000>;
 		};
 		opp-318750000 {