LU-498 pass oap instead of cookie to osc_teardown_async_page/osc_queue_async_io

LU-498 pass oap instead of cookie to osc_teardown_async_page/osc_queue_async_io

Now that queue_async_io & teardown_async_page are not obd operations any
more, we don't need to use a cookie and can just pass the correct type.

Change-Id: Iaf2ddf48bfee5c386064bb30e5392345c074c827
Signed-off-by: Johann Lombardi <johann@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/1081
Tested-by: Hudson
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jinshan Xiong <jay@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>