LU-753 obdfilter: improper LASSERT in filter_commitrw_write()

LU-753 obdfilter: improper LASSERT in filter_commitrw_write()

In rare cases fsfilt_commit_wait() will wake up and return after the
transaction has finished its work and updated j_commit_sequence but
the commit callbacks have not been run yet. Which will trigger the
LASSERT(oti->oti_transno <= obd->obd_last_committed) improperly.

We should just wait for the commit callback finished instead of put
an improper LASSERT here.

Signed-off-by: Niu Yawei <niu@whamcloud.com>
Change-Id: Ibd5add8d352d2e7598be49b0bf8fa37d40ce6e1f
Reviewed-on: http://review.whamcloud.com/1583
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Jinshan Xiong <jay@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>