Make sure we only reallocate buffers on a genuine port definition change.

Change-Id: I434be98700e5d9333f75a3a9a8c78f1acc7e7247
related-to-bug: 2953523
diff --git a/media/libstagefright/OMXCodec.cpp b/media/libstagefright/OMXCodec.cpp
index 9d45c80..f68c08a 100644
--- a/media/libstagefright/OMXCodec.cpp
+++ b/media/libstagefright/OMXCodec.cpp
@@ -1811,7 +1811,9 @@
 
         case OMX_EventPortSettingsChanged:
         {
-            onPortSettingsChanged(data1);
+            if (data2 == 0 || data2 == OMX_IndexParamPortDefinition) {
+                onPortSettingsChanged(data1);
+            }
             break;
         }