ide: make ide_hwif_t.ide_dma_{host_off,off_quietly} void (v2)

* since ide_hwif_t.ide_dma_{host_off,off_quietly} always return '0'
  make these functions void and while at it drop "ide_" prefix
* fix comment for __ide_dma_off_quietly()
* make __ide_dma_{host_off,off_quietly,off}() void and drop "__" prefix

v2:
* while at it rename atiixp_ide_dma_host_off() to atiixp_dma_host_off(),
  sgiioc4_ide_dma_{host_off,off_quietly}() to sgiioc4_dma_{host_off,off_quietly}()
  and sl82c105_ide_dma_off_quietly() to sl82c105_dma_off_quietly()
  [ Noticed by Sergei Shtylyov <sshtylyov@ru.mvista.com>. ]

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

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index be6d818..4e59239 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -1970,7 +1970,7 @@
 		printk(KERN_ERR "ide-tape: The tape wants to issue more "
 				"interrupts in DMA mode\n");
 		printk(KERN_ERR "ide-tape: DMA disabled, reverting to PIO\n");
-		(void)__ide_dma_off(drive);
+		ide_dma_off(drive);
 		return ide_do_reset(drive);
 	}
 	/* Get the number of bytes to transfer on this interrupt. */
@@ -2176,7 +2176,7 @@
 	if (test_and_clear_bit(PC_DMA_ERROR, &pc->flags)) {
 		printk(KERN_WARNING "ide-tape: DMA disabled, "
 				"reverting to PIO\n");
-		(void)__ide_dma_off(drive);
+		ide_dma_off(drive);
 	}
 	if (test_bit(PC_DMA_RECOMMENDED, &pc->flags) && drive->using_dma)
 		dma_ok = !hwif->dma_setup(drive);