ide: rework the code for selecting the best DMA transfer mode (v3)

Depends on the "ide: fix UDMA/MWDMA/SWDMA masks" patch.

* add ide_hwif_t.udma_filter hook for filtering UDMA mask
  (use it in alim15x3, hpt366, siimage and serverworks drivers)
* add ide_max_dma_mode() for finding best DMA mode for the device
  (loosely based on some older libata-core.c code)
* convert ide_dma_speed() users to use ide_max_dma_mode()
* make ide_rate_filter() take "ide_drive_t *drive" as an argument instead
  of "u8 mode" and teach it to how to use UDMA mask to do filtering
* use ide_rate_filter() in hpt366 driver
* remove no longer needed ide_dma_speed() and *_ratemask()
* unexport eighty_ninty_three()

v2:
* rename ->filter_udma_mask to ->udma_filter
  [ Suggested by Sergei Shtylyov <sshtylyov@ru.mvista.com>. ]

v3:
* updated for scc_pata driver (fixes XFER_UDMA_6 filtering for user-space
  originated transfer mode change requests when 100MHz clock is used)

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/hpt34x.c b/drivers/ide/pci/hpt34x.c
index 924eaa3..473e1b3 100644
--- a/drivers/ide/pci/hpt34x.c
+++ b/drivers/ide/pci/hpt34x.c
@@ -43,15 +43,10 @@
 
 #define HPT343_DEBUG_DRIVE_INFO		0
 
-static u8 hpt34x_ratemask (ide_drive_t *drive)
-{
-	return 1;
-}
-
 static int hpt34x_tune_chipset (ide_drive_t *drive, u8 xferspeed)
 {
 	struct pci_dev *dev	= HWIF(drive)->pci_dev;
-	u8 speed	= ide_rate_filter(hpt34x_ratemask(drive), xferspeed);
+	u8 speed = ide_rate_filter(drive, xferspeed);
 	u32 reg1= 0, tmp1 = 0, reg2 = 0, tmp2 = 0;
 	u8			hi_speed, lo_speed;
 
@@ -98,7 +93,7 @@
 
 static int config_chipset_for_dma (ide_drive_t *drive)
 {
-	u8 speed = ide_dma_speed(drive, hpt34x_ratemask(drive));
+	u8 speed = ide_max_dma_mode(drive);
 
 	if (!(speed))
 		return 0;