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: NMitch Williams <mitch.a.williams@intel.com>
Signed-off-by: NCatherine Sullivan  <catherine.sullivan@intel.com>
Tested-by: NKavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>