E100: work around the driver using streaming DMA mapping for RX descriptors.

E100 places it's RX packet descriptors inside skb->data and uses them
with bidirectional streaming DMA mapping. Unfortunately it fails to
transfer skb->data ownership to the device after it reads the
descriptor's status, breaking on non-coherent (e.g., ARM) platforms.

This have to be converted to use coherent memory for the descriptors.
Signed-off-by: Krzysztof Halasa <khc@pm.waw.pl>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/e100.c

@@ -1897,6 +1897,9 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
 
 			if (ioread8(&nic->csr->scb.status) & rus_no_res)
 				nic->ru_running = RU_SUSPENDED;
+		pci_dma_sync_single_for_device(nic->pdev, rx->dma_addr,
+					       sizeof(struct rfd),
+					       PCI_DMA_BIDIRECTIONAL);
 		return -ENODATA;
 	}