[cleanup] Convert XMALLOC/memset to XCALLOC

Simple conversion of XMALLOC/memset to XCALLOC
diff --git a/ospfd/ospf_snmp.c b/ospfd/ospf_snmp.c
index c47d432..5a0aea1 100644
--- a/ospfd/ospf_snmp.c
+++ b/ospfd/ospf_snmp.c
@@ -1405,11 +1405,7 @@
 static struct ospf_snmp_if *
 ospf_snmp_if_new ()
 {
-  struct ospf_snmp_if *osif;
-
-  osif = XMALLOC (0, sizeof (struct ospf_snmp_if));
-  memset (osif, 0, sizeof (struct ospf_snmp_if));
-  return osif;
+  return XCALLOC (0, sizeof (struct ospf_snmp_if));
 }
 
 static void