igb: re-order queues to support cleaner use of ivar on 82576

The 82576 adapter orders the queues in pairs when virtualization is in use.
The queue ordering previously conflicted with the ordering when sr-iov was
enabled.  This new ordering allows a PF to allocate 2 queues without using
any VF resources.

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>