xfs: attr forks require attr, not attr2

It turns out that I misunderstood the difference between the attr and
attr2 feature bits.  "attr" means that at some point an attr fork was
created somewhere in the filesystem.  "attr2" means that inodes have
variable-sized forks, but says nothing about whether or not there
actually /are/ attr forks in the system.

If we have an attr fork, we only need to check that attr is set.

Fixes: 99d9d8d0 ("xfs: scrub inode block mappings")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>