i40e/i40evf: Use dma_set_mask_and_coherent

In Linux 3.13, dma_set_mask_and_coherent was introduced, and we have
been encouraged to use it. It simplifies the DMA mapping code a bit as
well.

Change-ID: I66e340245af7d0dedfa8b40fec1f5e352754432e
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>