arm64: dts: mediatek: mt8183-kukui: Couple VGPU and VSRAM_GPU regulators

Add coupling for these regulators, as they have a strict voltage output
relation to satisfy in order to ensure GPU stable operation.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230301095523.428461-2-angelogioacchino.delregno@collabora.comSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi

@@ -294,7 +294,6 @@ dsi_out: endpoint {
 
 &gpu {
 	mali-supply = <&mt6358_vgpu_reg>;
-	sram-supply = <&mt6358_vsram_gpu_reg>;
 };
 
 &i2c0 {
@@ -401,6 +400,11 @@ &mt6358codec {
 	Avdd-supply = <&mt6358_vaud28_reg>;
 };
 
+&mt6358_vgpu_reg {
+	regulator-coupled-with = <&mt6358_vsram_gpu_reg>;
+	regulator-coupled-max-spread = <100000>;
+};
+
 &mt6358_vsim1_reg {
 	regulator-min-microvolt = <2700000>;
 	regulator-max-microvolt = <2700000>;
@@ -411,6 +415,11 @@ &mt6358_vsim2_reg {
 	regulator-max-microvolt = <2700000>;
 };
 
+&mt6358_vsram_gpu_reg {
+	regulator-coupled-with = <&mt6358_vgpu_reg>;
+	regulator-coupled-max-spread = <100000>;
+};
+
 &pio {
 	aud_pins_default: audiopins {
 		pins_bus {