BugLink: http://bugs.launchpad.net/bugs/1531539

We no longer require the two-pass setup for block integrity.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 4b9d5b15)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>