Add maxVirtualDisplaySize to configStore

Change-Id: I2c97995edda77b0044d3eaf394080bf7be6c0d77
diff --git a/configstore/1.0/ISurfaceFlingerConfigs.hal b/configstore/1.0/ISurfaceFlingerConfigs.hal
index ce967ee..1eaa4e9 100644
--- a/configstore/1.0/ISurfaceFlingerConfigs.hal
+++ b/configstore/1.0/ISurfaceFlingerConfigs.hal
@@ -84,4 +84,10 @@
      * GL composition.
      */
     useHwcForRGBtoYUV() generates(OptionalBool value);
+
+    /*
+     *  Maximum dimension supported by HWC for virtual display.
+     *  Must be equals to min(max_width, max_height).
+     */
+    maxVirtualDisplaySize() generates (OptionalUInt64 value);
 };