[XFS] Catch errors from xfs_acl_setmode().

Propagate the error status from xfs_acl_setmode() so that callers know if
the ACl was set correctly or not.

SGI-PV: 980084
SGI-Modid: xfs-linux-melb:xfs-kern:30792a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>