time/debug: Fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic at
once.

Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

kernel/time/test_udelay.c

···
 static void __exit udelay_test_exit(void)
 {
 	mutex_lock(&udelay_test_lock);
-	debugfs_remove(debugfs_lookup(DEBUGFS_FILENAME, NULL));
+	debugfs_lookup_and_remove(DEBUGFS_FILENAME, NULL);
 	mutex_unlock(&udelay_test_lock);
 }