The IDE core always sets ->dn correctly so changing it is never
required.

Setting it to a different value than assigned by IDE core is very likely
to result in data corruption (due to wrong transfer timings being set on
the controller etc.)
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Tested-by: NBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>