Fix online switching issue with cfq v2.  It does deferred clearing of
e->elevator_data, which screws up the current io scheduler.  It does not
have to, so just remove it.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>