it is reported that code hit DMA-API errors on 3.8-rc6+,
(see https://bugzilla.redhat.com/show_bug.cgi?id=908436, and
     https://bugzilla.redhat.com/show_bug.cgi?id=908550)

this patch just adds error handler for
    pci_map_single and skb_frag_dma_map.
Signed-off-by: xiong <xiong@qca.qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>