[PATCH] correct dma_set_mask return code in DMA-API.txt

The documentation says dma_set_api() returns 1 on success and
0 on error, which is plain wrong, standard kernel return codes
are used instead (0 on ok, -ESOMETHING on error).

Documentation/DMA-API.txt

@@ -160,7 +160,7 @@ pci_set_dma_mask(struct pci_device *dev, u64 mask)
 Checks to see if the mask is possible and updates the device
 parameters if it is.
 
-Returns: 1 if successful and 0 if not
+Returns: 0 if successful and a negative error if not.
 
 u64
 dma_get_required_mask(struct device *dev)