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/scc_pata.c b/drivers/ide/pci/scc_pata.c
index eeb0a6d..a19687c 100644
--- a/drivers/ide/pci/scc_pata.c
+++ b/drivers/ide/pci/scc_pata.c
@@ -231,16 +231,15 @@
 /**
  *	scc_tune_chipset	-	tune a drive DMA mode
  *	@drive: Drive to set up
- *	@xferspeed: speed we want to achieve
+ *	@speed: speed we want to achieve
  *
  *	Load the timing settings for this device mode into the
  *	controller.
  */
 
-static int scc_tune_chipset(ide_drive_t *drive, byte xferspeed)
+static int scc_tune_chipset(ide_drive_t *drive, const u8 speed)
 {
 	ide_hwif_t *hwif = HWIF(drive);
-	u8 speed = ide_rate_filter(drive, xferspeed);
 	struct scc_ports *ports = ide_get_hwifdata(hwif);
 	unsigned long ctl_base = ports->ctl;
 	unsigned long cckctrl_port = ctl_base + 0xff0;