igb: fix unused external references introduced with sr-iov changes

There were several unused external references added with the sr-iov
enablement changes.  This patch changes all those references to static
local references.

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>