[cleanup] Convert XMALLOC/memset to XCALLOC

Simple conversion of XMALLOC/memset to XCALLOC
diff --git a/ospfd/ospf_zebra.c b/ospfd/ospf_zebra.c
index e27f139..150ffac 100644
--- a/ospfd/ospf_zebra.c
+++ b/ospfd/ospf_zebra.c
@@ -1113,10 +1113,7 @@
 static struct ospf_distance *
 ospf_distance_new (void)
 {
-  struct ospf_distance *new;
-  new = XMALLOC (MTYPE_OSPF_DISTANCE, sizeof (struct ospf_distance));
-  memset (new, 0, sizeof (struct ospf_distance));
-  return new;
+  return XCALLOC (MTYPE_OSPF_DISTANCE, sizeof (struct ospf_distance));
 }
 
 static void