libxfs: clean up _calc_dquots_per_chunk

commit 58d789678546d46d7bbd809dd7dab417c0f23655 upstream.

The function xfs_calc_dquots_per_chunk takes a parameter in units
of basic blocks.  The kernel seems to get the units wrong, but
userspace got 'fixed' by commenting out the unnecessary conversion.
Fix both.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>