Use ide_config_drive_speed() instead of pmac_ide_do_setfeature() and remove
the latter, also ide-iops.c::__ide_wait_stat() could be static again.
Since for IDE PMAC host driver IDE_CONTROL_REG is always true, device's
->quirk_list is always zero and ->ide_dma_host_{on,off} are nops than
the only changes in behavior are:
* if PIO mode is set then ->dma_off_queitly is called to disable DMA
* if setting transfer mode fails ide_dump_status() is called to dump status
v2:
* IDE PMAC controllers allow separate PIO and DMA timings and PPC userland
depends on this fact, and calls "hdparm -p" without calling "hdparm -d".
Therefore to compensate for DMA being disabled by ide_config_drive_speed()
for PIO modes:
- add IDE_HFLAG_SET_PIO_MODE_KEEP_DMA flag and set it in PMAC host driver
- add handling of the new flag to ide-io.c::do_special()
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>