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/pci/it821x.c b/drivers/ide/pci/it821x.c
index 790233d..9286c99 100644
--- a/drivers/ide/pci/it821x.c
+++ b/drivers/ide/pci/it821x.c
@@ -720,7 +720,8 @@
 		.init_hwif	= init_hwif_it821x,	\
 		.autodma	= AUTODMA,		\
 		.bootable	= ON_BOARD,		\
-		.fixup	 	= it821x_fixups		\
+		.fixup	 	= it821x_fixups,	\
+		.pio_mask	= ATA_PIO4,		\
 	}
 
 static ide_pci_device_t it821x_chipsets[] __devinitdata = {