igb: do not re-register DCA requester on device reset

The current driver is re-registering the DCA requester after every reset.
Instead of doing this we should only be updating the on board DCA registers
and not unregistering/re-registering our requester.

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>