st/mesa: stop calling _mesa_init_buffer_object_functions()

After calling this we were then overriding all the functions with
st versions.

Reviewed-by: Eric Anholt <eric@anholt.net>

src/mesa/state_tracker/st_cb_bufferobjects.c

@@ -583,9 +583,6 @@ void
 st_init_bufferobject_functions(struct pipe_screen *screen,
                                struct dd_function_table *functions)
 {
-   /* plug in default driver fallbacks (such as for ClearBufferSubData) */
-   _mesa_init_buffer_object_functions(functions);
-
    functions->NewBufferObject = st_bufferobj_alloc;
    functions->DeleteBuffer = st_bufferobj_free;
    functions->BufferData = st_bufferobj_data;