ixgbe: move adapter into pci_dev driver data instead of netdev

This change moves an adapter pointer into the private portion of the
pci_dev instead of a pointer to the netdev. The reason for this change is
because in most cases we just want the adapter anyway. In addition as we
start moving toward multiple netdevs per port we may want to move the
adapter pointer out of the netdevs entirely.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>