chore(gx): use GxBlend_AlphaKey for GxRs_BlendingMode

src/gx/CGxDevice.cpp

@@ -333,7 +333,7 @@ void CGxDevice::ICursorDraw() {
     // Turn off everything
     GxRsSet(GxRs_PolygonOffset, 0);
     GxRsSet(GxRs_NormalizeNormals, 0);
-    GxRsSet(GxRs_BlendingMode, 1);
+    GxRsSet(GxRs_BlendingMode, GxBlend_AlphaKey);
     GxRsSetAlphaRef();
     GxRsSet(GxRs_Lighting, 0);
     GxRsSet(GxRs_Fog, 0);