net/sonic: Use dma_mapping_error()

With CONFIG_DMA_API_DEBUG=y, calling sonic_open() produces the
message, "DMA-API: device driver failed to check map error".
Add the missing dma_mapping_error() call.

Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Acked-by: NThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/natsemi/sonic.c

@@ -84,7 +84,7 @@ static int sonic_open(struct net_device *dev)
 	for (i = 0; i < SONIC_NUM_RRS; i++) {
 		dma_addr_t laddr = dma_map_single(lp->device, skb_put(lp->rx_skb[i], SONIC_RBSIZE),
 		                                  SONIC_RBSIZE, DMA_FROM_DEVICE);
-		if (!laddr) {
+		if (dma_mapping_error(lp->device, laddr)) {
 			while(i > 0) { /* free any that were mapped successfully */
 				i--;
 				dma_unmap_single(lp->device, lp->rx_laddr[i], SONIC_RBSIZE, DMA_FROM_DEVICE);