fib: Fix fib zone and its hash leak on namespace stop

When we stop a namespace we flush the table and free one, but the
added fn_zone-s (and their hashes if grown) are leaked. Need to free.
Tries releases all its stuff in the flushing code.

Shame on us - this bug exists since the very first make-fib-per-net
patches in 2.6.27 :(

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index b144508..200eb53 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1797,6 +1797,11 @@
 	return found;
 }
 
+void fib_free_table(struct fib_table *tb)
+{
+	kfree(tb);
+}
+
 void fib_table_select_default(struct fib_table *tb,
 			      const struct flowi *flp,
 			      struct fib_result *res)