ARM: dmabounce: simplify dma_set_mask()

Simplify the dmabounce specific code in dma_set_mask().  We can just
omit setting the dma mask if dmabounce is enabled (we will have already
set dma mask via callbacks when the device is created in that case.)
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/dma-mapping.h

@@ -133,18 +133,12 @@ static inline int dma_supported(struct device *dev, u64 mask)
 
 static inline int dma_set_mask(struct device *dev, u64 dma_mask)
 {
-#ifdef CONFIG_DMABOUNCE
-	if (dev->archdata.dmabounce) {
-		if (dma_mask >= ISA_DMA_THRESHOLD)
-			return 0;
-		else
-			return -EIO;
-	}
-#endif
 	if (!dev->dma_mask || !dma_supported(dev, dma_mask))
 		return -EIO;
 
+#ifndef CONFIG_DMABOUNCE
 	*dev->dma_mask = dma_mask;
+#endif
 
 	return 0;
 }