Remove obsolete comment from QDataStream test.

The removed comment was introduced before the tests were imported into
the Qt repository in 2006 and seems to relate to a test failure that no
longer occurs.

Change-Id: I01f372f6a4f48110711f4f2a86e73acfb7134e24
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>

tests/auto/corelib/io/qdatastream/tst_qdatastream.cpp

@@ -1539,12 +1539,6 @@ void tst_QDataStream::stream_QPen_data()
 
 void tst_QDataStream::stream_QPen()
 {
-    /*
-    edba:
-    data6 fails because the width is clipped to a byte (max 255) in the datastream.
-    This limitation is not documented.
-    */
-
     STREAM_IMPL(QPen);
 }