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/sl82c105.c b/drivers/ide/pci/sl82c105.c
index 0947cab..9f425b0 100644
--- a/drivers/ide/pci/sl82c105.c
+++ b/drivers/ide/pci/sl82c105.c
@@ -113,7 +113,7 @@
 /*
  * Configure the drive and chipset for a new transfer speed.
  */
-static int sl82c105_tune_chipset(ide_drive_t *drive, u8 speed)
+static int sl82c105_tune_chipset(ide_drive_t *drive, const u8 speed)
 {
 	static u16 mwdma_timings[] = {0x0707, 0x0201, 0x0200};
 	u16 drv_ctrl;
@@ -121,8 +121,6 @@
  	DBG(("sl82c105_tune_chipset(drive:%s, speed:%s)\n",
 	     drive->name, ide_xfer_verbose(speed)));
 
-	speed = ide_rate_filter(drive, speed);
-
 	switch (speed) {
 	case XFER_MW_DMA_2:
 	case XFER_MW_DMA_1: