pty: Fix allocation failure double free

The updating and moving around of the pty code added a bug where both the
helper and caller free the main tty struct (the pty driver must free the
o_tty pair itself however).

Signed-off-by: Alan Cox <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/pty.c

···
 	module_put(o_tty->driver->owner);
 	free_tty_struct(o_tty);
 	pty_unix98_shutdown(tty);
-	free_tty_struct(tty);
-	module_put(driver->owner);
 	return -ENOMEM;
 }