QtConcurrent example: remove unneeded explicit template type

I show this code during trainings and this explicit template type
just makes the line of code more complex than it has to be.

Change-Id: I294c65f48967e54c67d9c3b8e1de96c3c2495a5b
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

examples/qtconcurrent/map/main.cpp

@@ -64,7 +64,7 @@ int main(int argc, char *argv[])
 
     // Use QtConcurrentBlocking::mapped to apply the scale function to all the
     // images in the list.
-    QList<QImage> thumbnails = QtConcurrent::blockingMapped<QList<QImage> >(images, scale);
+    QList<QImage> thumbnails = QtConcurrent::blockingMapped(images, scale);
 
     return 0;
 }