xfs: simplify a check in xfs_ioctl_setattr_check_cowextsize

commit 5e28aafe708ba3e388f92a7148093319d3521c2f upstream.

Only v5 file systems can have the reflink feature, and those will
always use the large dinode format.  Remove the extra check for the
inode version.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>