libata: kill qc->nsect and cursect

libata used two separate sets of variables to record request size and
current offset for ATA and ATAPI.  This is confusing and fragile.
This patch replaces qc->nsect/cursect with qc->nbytes/curbytes and
kills them.  Also, ata_pio_sector() is updated to use bytes for
qc->cursg_ofs instead of sectors.  The field used to be used in bytes
for ATAPI and in sectors for ATA.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/pata_pdc202xx_old.c b/drivers/ata/pata_pdc202xx_old.c
index ad691b9..ba982ba 100644
--- a/drivers/ata/pata_pdc202xx_old.c
+++ b/drivers/ata/pata_pdc202xx_old.c
@@ -189,10 +189,7 @@
 	/* Cases the state machine will not complete correctly without help */
 	if ((tf->flags & ATA_TFLAG_LBA48) ||  tf->protocol == ATA_PROT_ATAPI_DMA)
 	{
-		if (tf->flags & ATA_TFLAG_LBA48)
-			len = qc->nsect * 512;
-		else
-			len = qc->nbytes;
+		len = qc->nbytes;
 
 		if (tf->flags & ATA_TFLAG_WRITE)
 			len |= 0x06000000;