igb: convert igb from using PCI DMA functions to using DMA API functions

This patch makes it so that igb now uses the DMA API functions instead of
the PCI API functions.  To do this the pci_dev pointer that was in the
rings has been replaced with a device pointer, and as a result all
references to [tr]x_ring->pdev have been replaced with [tr]x_ring->dev.

This patch is based of of work originally done by Nicholas Nunley.
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>