tty has no longer flip buffers accessible externally. Fix it by moving the
code to the tty_*flip* helpers.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>