[cleanup] Convert XMALLOC/memset to XCALLOC

Simple conversion of XMALLOC/memset to XCALLOC
diff --git a/zebra/rtadv.c b/zebra/rtadv.c
index 4bdb83d..e1fd0dc 100644
--- a/zebra/rtadv.c
+++ b/zebra/rtadv.c
@@ -84,10 +84,7 @@
 static struct rtadv *
 rtadv_new (void)
 {
-  struct rtadv *new;
-  new = XMALLOC (MTYPE_TMP, sizeof (struct rtadv));
-  memset (new, 0, sizeof (struct rtadv));
-  return new;
+  return XCALLOC (MTYPE_TMP, sizeof (struct rtadv));
 }
 
 static void
@@ -529,12 +526,7 @@
 static struct rtadv_prefix *
 rtadv_prefix_new ()
 {
-  struct rtadv_prefix *new;
-
-  new = XMALLOC (MTYPE_RTADV_PREFIX, sizeof (struct rtadv_prefix));
-  memset (new, 0, sizeof (struct rtadv_prefix));
-
-  return new;
+  return XCALLOC (MTYPE_RTADV_PREFIX, sizeof (struct rtadv_prefix));
 }
 
 static void