[libata] Use ATA_UDMAx standard masks when filling driver's udma_mask info

The ATA_UDMAx masks are self-documenting, and far better than manually
writing in the hex mask.

Note that pata_it8213 mask differed from the comment.  Added a FIXME there.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/pata_sil680.c b/drivers/ata/pata_sil680.c
index 9b645c5..b0cd52d 100644
--- a/drivers/ata/pata_sil680.c
+++ b/drivers/ata/pata_sil680.c
@@ -349,7 +349,7 @@
 		.flags = ATA_FLAG_SLAVE_POSS,
 		.pio_mask = 0x1f,
 		.mwdma_mask = 0x07,
-		.udma_mask = 0x7f,
+		.udma_mask = ATA_UDMA6,
 		.port_ops = &sil680_port_ops
 	};
 	static const struct ata_port_info info_slow = {
@@ -357,7 +357,7 @@
 		.flags = ATA_FLAG_SLAVE_POSS,
 		.pio_mask = 0x1f,
 		.mwdma_mask = 0x07,
-		.udma_mask = 0x3f,
+		.udma_mask = ATA_UDMA5,
 		.port_ops = &sil680_port_ops
 	};
 	const struct ata_port_info *ppi[] = { &info, NULL };