MIPS/jazzdma: return error code from jazz_dma_map_sg()

The .map_sg() op now expects an error code instead of zero on failure.

vdma_alloc() may fail for different reasons, but since it only supports
indicating an error via a return of DMA_MAPPING_ERROR, we coalesce the
different reasons into -EIO as is documented on dma_map_sgtable().
Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

arch/mips/jazz/jazzdma.c

@@ -552,7 +552,7 @@ static int jazz_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 				dir);
 		sg->dma_address = vdma_alloc(sg_phys(sg), sg->length);
 		if (sg->dma_address == DMA_MAPPING_ERROR)
-			return 0;
+			return -EIO;
 		sg_dma_len(sg) = sg->length;
 	}