[XFS] Put back the QUEUE_ORDERED_NONE test in the barrier check.

Put back the QUEUE_ORDERED_NONE test which caused us grief in sles when it
was taken out as, IIRC, it allowed md/lvm to be thought of as supporting
barriers when they weren't in some configurations. This patch will be
reverting what went in as part of a change for the SGI-pv 964544
(SGI-Modid: xfs-linux-melb:xfs-kern:28568a).

SGI-PV: 971783
SGI-Modid: xfs-linux-melb:xfs-kern:29882a

Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>