walleye: Boost GPU on EXPENSIVE_RENDERING power hint

We're using this hint for GPU-intensive blur, so it should boost the GPU
to a frequency high enough for that.

powerhint.json

@@ -505,6 +505,18 @@
       "Node": "CPULittleClusterMinFreq",
       "Duration": 0,
       "Value": "0"
+    },
+    {
+      "PowerHint": "EXPENSIVE_RENDERING",
+      "Node": "GPUMinFreq",
+      "Duration": 0,
+      "Value": "414000000"
+    },
+    {
+      "PowerHint": "EXPENSIVE_RENDERING",
+      "Node": "GPUMaxFreq",
+      "Duration": 0,
+      "Value": "710000000"
     }
   ]
 }