pata_atp867x: PIO support fixes

* use  8 clk setting for active clocks == 7 (was 12 clk)
* use 12 clk setting for active clocks > 12 (was  8 clk)
* do 66MHz bus fixup before mapping active clocks
* fix setup of PIO command timings

Acked-by: Jung-Ik (John) Lee <jilee@google.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>