TTY: tty_io, annotate locking functions

tty_write_lock and tty_write_unlock contain imbalanced locking. But
this is intentional, so mark them appropriately by
__acquires/__releases.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/tty/tty_io.c

@@ -962,12 +962,14 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
 }
 
 void tty_write_unlock(struct tty_struct *tty)
+	__releases(&tty->atomic_write_lock)
 {
 	mutex_unlock(&tty->atomic_write_lock);
 	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
 }
 
 int tty_write_lock(struct tty_struct *tty, int ndelay)
+	__acquires(&tty->atomic_write_lock)
 {
 	if (!mutex_trylock(&tty->atomic_write_lock)) {
 		if (ndelay)