mbuf leakage fix

[Loganaden Velvindron]

Hi,
>From netbsd.


Index: ip6_mroute.c
===================================================================
--- ip6_mroute.c	(revision 255947)
+++ ip6_mroute.c	(working copy)
@@ -616,7 +616,7 @@
 			for (rte = rt->mf6c_stall; rte != NULL; ) {
 				struct rtdetq *n = rte->next;
 
-				m_free(rte->m);
+				m_freem(rte->m);
 				free(rte, M_MRTABLE6);
 				rte = n;
 			}