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/pdc202xx_new.c b/drivers/ide/pci/pdc202xx_new.c
index 7c5544d..3787194 100644
--- a/drivers/ide/pci/pdc202xx_new.c
+++ b/drivers/ide/pci/pdc202xx_new.c
@@ -146,14 +146,12 @@
 	{ 0x1a, 0x01, 0xcb },	/* UDMA mode 6 */
 };
 
-static int pdcnew_tune_chipset(ide_drive_t *drive, u8 speed)
+static int pdcnew_tune_chipset(ide_drive_t *drive, const u8 speed)
 {
 	ide_hwif_t *hwif	= HWIF(drive);
 	u8 adj			= (drive->dn & 1) ? 0x08 : 0x00;
 	int			err;
 
-	speed = ide_rate_filter(drive, speed);
-
 	/*
 	 * Issue SETFEATURES_XFER to the drive first. PDC202xx hardware will
 	 * automatically set the timing registers based on 100 MHz PLL output.