ide: clear bmdma status in ide_intr() for ICHx controllers (revised #4)

patch 1/2 (revised):
- Fix drive->waiting_for_dma to work with CDB-intr devices.
- Do the dma status clearing in ide_intr() and add a new
  hwif->ide_dma_clear_irq for Intel ICHx controllers.

Revised per Alan, Sergei and Bart's advice.

Patch against 2.6.20-rc6. Tested ok on my ICH4 and pdc20275 adapters.
Please review/apply, thanks.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "Adam W. Hawks" <awhawks@us.ibm.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index c750f6c..65eb095 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -509,6 +509,7 @@
 	hwif->ide_dma_on		= tmp_hwif->ide_dma_on;
 	hwif->ide_dma_off_quietly	= tmp_hwif->ide_dma_off_quietly;
 	hwif->ide_dma_test_irq		= tmp_hwif->ide_dma_test_irq;
+	hwif->ide_dma_clear_irq		= tmp_hwif->ide_dma_clear_irq;
 	hwif->ide_dma_host_on		= tmp_hwif->ide_dma_host_on;
 	hwif->ide_dma_host_off		= tmp_hwif->ide_dma_host_off;
 	hwif->ide_dma_lostirq		= tmp_hwif->ide_dma_lostirq;