Fix tty_io.c send_break() to assert break for proper duration.  If driver
break_ctl() changes task state, then break may end prematurely.  USB serial
driver break_ctl() sends a URB, changing task state to TASK_RUNNING.
Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>