lib: remove error checking for debugfs_create_dir()

It is expected that most callers should _ignore_ the errors return by
debugfs_create_dir() in err_inject_init().

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Wang Ming <[e-mail]>
Cc: Akinobu Mita <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

lib/notifier-error-inject.c

···
 	notifier_err_inject_dir =
 		debugfs_create_dir("notifier-error-inject", NULL);
 
-	if (!notifier_err_inject_dir)
-		return -ENOMEM;
-
 	return 0;
 }