xfs: eager inode attr fork init needs attr feature awareness

The pitfalls of regression testing on a machine without realising
that selinux was disabled. Only set the attr fork during inode
allocation if the attr feature bits are already set on the
superblock.

Fixes: e6a688c3

 ("xfs: initialise attr fork on inode create")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>