drivers/char/tty_io.c: remove pty_sem

I couldn't find any users, so removing it..
Signed-off-by: NDaniel Walker <dwalker@mvista.com>
Acked-by: NAlan Cox <alan@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_io.c

@@ -3721,7 +3721,6 @@ static void initialize_tty_struct(struct tty_struct *tty)
 	tty->buf.head = tty->buf.tail = NULL;
 	tty_buffer_init(tty);
 	INIT_DELAYED_WORK(&tty->buf.work, flush_to_ldisc);
-	init_MUTEX(&tty->buf.pty_sem);
 	mutex_init(&tty->termios_mutex);
 	init_waitqueue_head(&tty->write_wait);
 	init_waitqueue_head(&tty->read_wait);

include/linux/tty.h

@@ -74,7 +74,6 @@ struct tty_buffer {
 
 struct tty_bufhead {
 	struct delayed_work work;
-	struct semaphore pty_sem;
 	spinlock_t lock;
 	struct tty_buffer *head;	/* Queue head */
 	struct tty_buffer *tail;	/* Active buffer */