ide: add PIO masks

* Add ATA_PIO[0-6] defines to <linux/ata.h>.

* Add ->pio_mask field to ide_pci_device_t and ide_hwif_t.

* Add PIO masks to host drivers.

<linux/ata.h> change ACK-ed by Jeff Garzik <jeff@garzik.org>.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/legacy/dtc2278.c b/drivers/ide/legacy/dtc2278.c
index 8c4c27e..6c01d95 100644
--- a/drivers/ide/legacy/dtc2278.c
+++ b/drivers/ide/legacy/dtc2278.c
@@ -123,6 +123,7 @@
 
 	hwif->serialized = 1;
 	hwif->chipset = ide_dtc2278;
+	hwif->pio_mask = ATA_PIO4;
 	hwif->tuneproc = &tune_dtc2278;
 	hwif->drives[0].no_unmask = 1;
 	hwif->drives[1].no_unmask = 1;