dmaengine: Fix a bug about BUG_ON() on DMA engine capability DMA_INTERRUPT.

The device->device_prep_dma_interrupt function is used by
DMA_INTERRUPT capability, not DMA_ZERO_SUM.

Signed-off-by: Zhang Wei <wei.zhang@freescale.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/dmaengine.c

@@ -357,7 +357,7 @@ int dma_async_device_register(struct dma_device *device)
 		!device->device_prep_dma_zero_sum);
 	BUG_ON(dma_has_cap(DMA_MEMSET, device->cap_mask) &&
 		!device->device_prep_dma_memset);
-	BUG_ON(dma_has_cap(DMA_ZERO_SUM, device->cap_mask) &&
+	BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
 		!device->device_prep_dma_interrupt);
 
 	BUG_ON(!device->device_alloc_chan_resources);