[XFS] Rework DMAPI bulkstat calls in such a way that we can directly

extract inline attributes out of the bulkstat buffer (for that case),
rather than using an (extremely expensive for large icount filesystems)
iget for fetching attrs.

SGI-PV: 944409
SGI-Modid: xfs-linux-melb:xfs-kern:26602a

Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>