[cleanup] Convert XMALLOC/memset to XCALLOC

Simple conversion of XMALLOC/memset to XCALLOC
diff --git a/vtysh/vtysh_user.c b/vtysh/vtysh_user.c
index e301505..58676c1 100644
--- a/vtysh/vtysh_user.c
+++ b/vtysh/vtysh_user.c
@@ -101,10 +101,7 @@
 struct vtysh_user *
 user_new ()
 {
-  struct vtysh_user *user;
-  user = XMALLOC (0, sizeof (struct vtysh_user));
-  memset (user, 0, sizeof (struct vtysh_user));
-  return user;
+  return XCALLOC (0, sizeof (struct vtysh_user));
 }
 
 void