it821x: use ide_get_pair_dev() helper

Because presence of the peer device was not checked in
it821x_set_pio_mode() PIO0 mode was used for taskfile PIO
in single device configurations.
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/it821x.c

@@ -167,12 +167,10 @@ static void it821x_clock_strategy(ide_drive_t *drive)
 	ide_hwif_t *hwif = drive->hwif;
 	struct pci_dev *dev = to_pci_dev(hwif->dev);
 	struct it821x_dev *itdev = ide_get_hwifdata(hwif);
-	ide_drive_t *pair;
+	ide_drive_t *pair = ide_get_pair_dev(drive);
 	int clock, altclock, sel = 0;
 	u8 unit = drive->dn & 1, v;
 
-	pair = &hwif->drives[1 - unit];
-
 	if(itdev->want[0][0] > itdev->want[1][0]) {
 		clock = itdev->want[0][1];
 		altclock = itdev->want[1][1];
@@ -239,15 +237,13 @@ static void it821x_set_pio_mode(ide_drive_t *drive, const u8 pio)
 {
 	ide_hwif_t *hwif = drive->hwif;
 	struct it821x_dev *itdev = ide_get_hwifdata(hwif);
-	ide_drive_t *pair;
+	ide_drive_t *pair = ide_get_pair_dev(drive);
 	u8 unit = drive->dn & 1, set_pio = pio;
 
 	/* Spec says 89 ref driver uses 88 */
 	static u16 pio_timings[]= { 0xAA88, 0xA382, 0xA181, 0x3332, 0x3121 };
 	static u8 pio_want[]    = { ATA_66, ATA_66, ATA_66, ATA_66, ATA_ANY };
 
-	pair = &hwif->drives[1 - unit];
-
 	/*
 	 * Compute the best PIO mode we can for a given device. We must
 	 * pick a speed that does not cause problems with the other device