Fix: Wrong change in refactor of paint smear brush

Mistake in 437cb33a73.
Found while investigating #129504. Personally I don't notice
a change in behavior, but the original code, as convoluted as it
was/is, clearly tried to iterate over neighbors of neighbors rather
than iterating over neighbors twice.

Pull Request: https://projects.blender.org/blender/blender/pulls/129557

source/blender/editors/sculpt_paint/sculpt_paint_color.cc

@@ -770,7 +770,7 @@ static void do_smear_brush_task(const Depsgraph &depsgraph,
                                                                  corner_verts,
                                                                  vert_to_face_map,
                                                                  attribute_data.hide_poly,
-                                                                 vert,
+                                                                 neigbor,
                                                                  neighbor_neighbors))
       {
         if (neighbor_neighbor == vert) {