[cleanup] Convert XMALLOC/memset to XCALLOC

Simple conversion of XMALLOC/memset to XCALLOC
diff --git a/ospf6d/ospf6_asbr.c b/ospf6d/ospf6_asbr.c
index 37b912b..685b147 100644
--- a/ospf6d/ospf6_asbr.c
+++ b/ospf6d/ospf6_asbr.c
@@ -504,8 +504,7 @@
   memcpy (&route->prefix, prefix, sizeof (struct prefix));
 
   info = (struct ospf6_external_info *)
-    XMALLOC (MTYPE_OSPF6_EXTERNAL_INFO, sizeof (struct ospf6_external_info));
-  memset (info, 0, sizeof (struct ospf6_external_info));
+    XCALLOC (MTYPE_OSPF6_EXTERNAL_INFO, sizeof (struct ospf6_external_info));
   route->route_option = info;
   info->id = ospf6->external_id++;