[ATM]: Fix clip module reload crash.

net/atm/clip.c crashes the kernel if it (module) is loaded, removed,
and then loaded again.  Its exit call to neigh_table_clear()
should destroy the cache after freeing it.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/neighbour.c

@@ -1438,6 +1438,9 @@ int neigh_table_clear(struct neigh_table *tbl)
 	free_percpu(tbl->stats);
 	tbl->stats = NULL;
 
+	kmem_cache_destroy(tbl->kmem_cachep);
+	tbl->kmem_cachep = NULL;
+
 	return 0;
 }