lib/fault-inject-usercopy.c: use PTR_ERR_OR_ZERO() to simplify code

Use the standard error pointer macro to shorten the code and simplify.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Xichao Zhao <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

lib/fault-inject-usercopy.c

···
 
 	dir = fault_create_debugfs_attr("fail_usercopy", NULL,
 					&fail_usercopy.attr);
-	if (IS_ERR(dir))
-		return PTR_ERR(dir);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(dir);
 }
 
 late_initcall(fail_usercopy_debugfs);