usb: remove bad dput after dentry_unhash

Commit 64252c75 removed the useless dget from dentry_unhash but didn't
fix up this caller in the usb code.  There used to be exactly one dput per
dentry_unhash call; now there are none.
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/usb/core/inode.c

@@ -389,7 +389,6 @@ static int usbfs_rmdir(struct inode *dir, struct dentry *dentry)
 	mutex_unlock(&inode->i_mutex);
 	if (!error)
 		d_delete(dentry);
-	dput(dentry);
 	return error;
 }