ixgb: remove use of skb_dma_map from ixgb

skb_dma_map is incompatible with HW iommu due to the fact that multiple
mappings can result in different results each time.  For this reason it is
best to just remove use of these function calls.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>