ide: add ide_tune_dma() helper

After reworking the code responsible for selecting the best DMA
transfer mode it is now possible to add generic ide_tune_dma() helper.

Convert some IDE PCI host drivers to use it (the ones left need more work).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/include/linux/ide.h b/include/linux/ide.h
index 23ab4dc0..d03fa2d 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1277,6 +1277,7 @@
 int __ide_dma_good_drive(ide_drive_t *);
 int ide_use_dma(ide_drive_t *);
 u8 ide_max_dma_mode(ide_drive_t *);
+int ide_tune_dma(ide_drive_t *);
 void ide_dma_off(ide_drive_t *);
 void ide_dma_verbose(ide_drive_t *);
 int ide_set_dma(ide_drive_t *);
@@ -1304,6 +1305,7 @@
 #else
 static inline int ide_use_dma(ide_drive_t *drive) { return 0; }
 static inline u8 ide_max_dma_mode(ide_drive_t *drive) { return 0; }
+static inline int ide_tune_dma(ide_drive_t *drive) { return 0; }
 static inline void ide_dma_off(ide_drive_t *drive) { ; }
 static inline void ide_dma_verbose(ide_drive_t *drive) { ; }
 static inline int ide_set_dma(ide_drive_t *drive) { return 1; }