nir/dominance: Use _mesa_set_clear instead ofhand-rolling it

Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6750>
diff --git a/src/compiler/nir/nir_dominance.c b/src/compiler/nir/nir_dominance.c
index 0f4cd5a..4ea46f8 100644
--- a/src/compiler/nir/nir_dominance.c
+++ b/src/compiler/nir/nir_dominance.c
@@ -46,9 +46,7 @@
    block->dom_pre_index = UINT32_MAX;
    block->dom_post_index = 0;
 
-   set_foreach(block->dom_frontier, entry) {
-      _mesa_set_remove(block->dom_frontier, entry);
-   }
+   _mesa_set_clear(block->dom_frontier, NULL);
 
    return true;
 }