st/fbo: use pipe_surface_release instead of pipe_surface_reference

pipe_surface_reference have problems with deleted contexts,
so use of pipe_surface_release might be more appropriate.

Fixes Wasteland 2 Director's Cut crash on start.

Cc: mesa-stable@lists.freedesktop.org

Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/state_tracker/st_cb_fbo.c

@@ -456,7 +456,7 @@ st_update_renderbuffer_surface(struct st_context *st,
       surf_tmpl.u.tex.first_layer = first_layer;
       surf_tmpl.u.tex.last_layer = last_layer;
 
-      pipe_surface_reference(&strb->surface, NULL);
+      pipe_surface_release(pipe, &strb->surface);
 
       strb->surface = pipe->create_surface(pipe, resource, &surf_tmpl);
    }