clk: qcom: mmcc-msm8996: Properly describe GPU_GX gdsc

The GPU_GX GDSC depends on both GPU GDSC being enabled and that the
VDD_GX rail is powered, so update the description of the node to cover
these requirements.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lkml.kernel.org/r/20200417070044.1376212-3-bjorn.andersson@linaro.orgAcked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Documentation/devicetree/bindings/clock/qcom,mmcc.yaml

@@ -67,6 +67,10 @@ properties:
     description:
        Protected clock specifier list as per common clock binding
 
+  vdd-gfx-supply:
+    description:
+      Regulator supply for the GPU_GX GDSC
+
 required:
   - compatible
   - reg

drivers/clk/qcom/mmcc-msm8996.c

@@ -3064,7 +3064,9 @@ static struct gdsc gpu_gx_gdsc = {
 		.name = "gpu_gx",
 	},
 	.pwrsts = PWRSTS_OFF_ON,
+	.parent = &gpu_gdsc.pd,
 	.flags = CLAMP_IO,
+	.supply = "vdd-gfx",
 };
 
 static struct clk_regmap *mmcc_msm8996_clocks[] = {