ata_if_xfermask() word 51 fix

If word 53 bit 1 isn't set, the maximum PIO mode is indicated by
the upper 8 bits of word 51, not the lower 8 bits.  Fixes PIO mode
detection on old Compact Flash cards.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index a388a8d..cf70702 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1037,7 +1037,7 @@
 		 * the PIO timing number for the maximum. Turn it into
 		 * a mask.
 		 */
-		u8 mode = id[ATA_ID_OLD_PIO_MODES] & 0xFF;
+		u8 mode = (id[ATA_ID_OLD_PIO_MODES] >> 8) & 0xFF;
 		if (mode < 5)	/* Valid PIO range */
                 	pio_mask = (2 << mode) - 1;
 		else