After removing the skb_dma_map/unmap calls the exception handling in
igb_tx_map_adv is not correct.  The issue is that the count value was not
being correctly handled so as a result we were not rewinding the ring as
back as we should have been.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>