ide: move ide_rate_filter() calls to the upper layer (take 2)

* Move ide_rate_filter() calls from host drivers to IDE core.

* Make ide_rate_filter() static.

* Make 'speed' argument of ->speedproc const.

v2:
* Fix it8213_tune_chipset() comment.

There should be no functionality changes caused by this patch.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/via82cxxx.c b/drivers/ide/pci/via82cxxx.c
index ec9ad6e..e3bf907 100644
--- a/drivers/ide/pci/via82cxxx.c
+++ b/drivers/ide/pci/via82cxxx.c
@@ -158,15 +158,13 @@
  *	by upper layers.
  */
 
-static int via_set_drive(ide_drive_t *drive, u8 speed)
+static int via_set_drive(ide_drive_t *drive, const u8 speed)
 {
 	ide_drive_t *peer = HWIF(drive)->drives + (~drive->dn & 1);
 	struct via82cxxx_dev *vdev = pci_get_drvdata(drive->hwif->pci_dev);
 	struct ide_timing t, p;
 	unsigned int T, UT;
 
-	speed = ide_rate_filter(drive, speed);
-
 	if (speed != XFER_PIO_SLOW)
 		ide_config_drive_speed(drive, speed);