Fix incorrect warning message in QOpenGLBuffer

Change-Id: I932aa10814049e78da35ea12b7552bf676545c89
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

src/gui/opengl/qopenglbuffer.cpp

@@ -371,7 +371,7 @@ void QOpenGLBuffer::write(int offset, const void *data, int count)
 {
 #ifndef QT_NO_DEBUG
     if (!isCreated())
-        qWarning("QOpenGLBuffer::allocate(): buffer not created");
+        qWarning("QOpenGLBuffer::write(): buffer not created");
 #endif
     Q_D(QOpenGLBuffer);
     if (d->guard && d->guard->id())