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: 6556ff32f12d ("netdevsim: use IS_ERR instead of IS_ERR_OR_NULL for debugfs")
CC: Taehee Yoo <[e-mail]>
Signed-off-by: kbuild test robot <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/netdevsim/dev.c

···
 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)