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/cs5520.c b/drivers/ide/pci/cs5520.c
index 5079810..af67438 100644
--- a/drivers/ide/pci/cs5520.c
+++ b/drivers/ide/pci/cs5520.c
@@ -66,16 +66,15 @@
 	{1, 2, 1}
 };
 
-static int cs5520_tune_chipset(ide_drive_t *drive, u8 xferspeed)
+static int cs5520_tune_chipset(ide_drive_t *drive, const u8 speed)
 {
 	ide_hwif_t *hwif = HWIF(drive);
 	struct pci_dev *pdev = hwif->pci_dev;
-	u8 speed = ide_rate_filter(drive, xferspeed);
 	int pio = speed;
 	u8 reg;
 	int controller = drive->dn > 1 ? 1 : 0;
 	int error;
-	
+
 	switch(speed)
 	{
 		case XFER_PIO_4: