ide: make ide_hwif_t.ide_dma_host_on void (v2)

* since ide_hwif_t.ide_dma_host_on is called either when drive->using_dma == 1
  or when return value is discarded make it void, also drop "ide_" prefix
* make __ide_dma_host_on() void and drop "__" prefix

v2:
* while at it rename atiixp_ide_dma_host_on() to atiixp_dma_host_on()
  and sgiioc4_ide_dma_host_on() to sgiioc4_dma_host_on().
  [ Noticed by Sergei Shtylyov <sshtylyov@ru.mvista.com>. ]

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

diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index 6e146b5..b3c0818 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -509,7 +509,7 @@
 	hwif->dma_off_quietly		= tmp_hwif->dma_off_quietly;
 	hwif->ide_dma_test_irq		= tmp_hwif->ide_dma_test_irq;
 	hwif->ide_dma_clear_irq		= tmp_hwif->ide_dma_clear_irq;
-	hwif->ide_dma_host_on		= tmp_hwif->ide_dma_host_on;
+	hwif->dma_host_on		= tmp_hwif->dma_host_on;
 	hwif->dma_host_off		= tmp_hwif->dma_host_off;
 	hwif->ide_dma_lostirq		= tmp_hwif->ide_dma_lostirq;
 	hwif->ide_dma_timeout		= tmp_hwif->ide_dma_timeout;