ide: constify struct ide_dma_ops

* Export ide_dma_exec_cmd() and __ide_dma_test_irq().

* Constify struct ide_dma_ops.

* Always set hwif->dma_ops to &sff_dma_ops in ide_setup_dma()
  (it is later overriden by ide_init_port() if needed) and drop
  'const struct ide_port_info *d' argument.

While at it:

* Rename __ide_dma_test_irq() to ide_dma_test_irq().

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index 9504aa5..a317ca9 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -135,7 +135,7 @@
 	ide_hwif_t *hwif	= HWIF(drive);
 	struct ide_taskfile *tf = &task->tf;
 	ide_handler_t *handler = NULL;
-	struct ide_dma_ops *dma_ops = hwif->dma_ops;
+	const struct ide_dma_ops *dma_ops = hwif->dma_ops;
 
 	if (task->data_phase == TASKFILE_MULTI_IN ||
 	    task->data_phase == TASKFILE_MULTI_OUT) {