DMA-API: others: use dma_set_coherent_mask()

The correct way for a driver to specify the coherent DMA mask is
not to directly access the field in the struct device, but to use
dma_set_coherent_mask().  Only arch and bus code should access this
member directly.

Convert all direct write accesses to using the correct API.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
index acf6678..701c4c1 100644
--- a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
+++ b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c
@@ -664,8 +664,9 @@
 	}
 
 	/* set dma mask for device */
-	/* NOTE: this is a workaround for the hwmod not initializing properly */
-	dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+	ret = dma_set_coherent_mask(&dev->dev, DMA_BIT_MASK(32));
+	if (ret)
+		goto fail;
 
 	omap_dmm->dummy_pa = page_to_phys(omap_dmm->dummy_page);