- tty_hangup() itself schedules work, so there is no need to schedule hangup
  in the driver

- tty_wakeup(): it's safe to call it while in atomic, so that its
  schedule_work might be also wiped out
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>