ide-pmac: remove pmac_ide_do_setfeature() (take 2)

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>
diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index f7e976c..e5fc2e5 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -483,7 +483,7 @@
  * setting a timer to wake up at half second intervals thereafter,
  * until timeout is achieved, before timing out.
  */
-int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad, unsigned long timeout, u8 *rstat)
+static int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad, unsigned long timeout, u8 *rstat)
 {
 	ide_hwif_t *hwif = drive->hwif;
 	unsigned long flags;