igb: replace unecessary &adapter->hw with just hw where applicable

This patch just cleans up some unecessary references to the adapter->hw
member when it has already been placed in a local variable named hw.

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>