netdevsim: fix ptr_ret.cocci warnings

drivers/net/netdevsim/dev.c:937:1-3: WARNING: PTR_ERR_OR_ZERO can be used

 Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci

Fixes: 6556ff32 ("netdevsim: use IS_ERR instead of IS_ERR_OR_NULL for debugfs")
CC: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Nkbuild test robot <lkp@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/netdevsim/dev.c

@@ -934,9 +934,7 @@ int nsim_dev_port_del(struct nsim_bus_dev *nsim_bus_dev,
 int nsim_dev_init(void)
 {
 	nsim_dev_ddir = debugfs_create_dir(DRV_NAME, NULL);
-	if (IS_ERR(nsim_dev_ddir))
-		return PTR_ERR(nsim_dev_ddir);
-	return 0;
+	return PTR_ERR_OR_ZERO(nsim_dev_ddir);
 }
 
 void nsim_dev_exit(void)