igb: remove unused defines

This patch removes all of the unused defines from the .h files contained in
igb.  For some defines there was a use and so I plugged them into the correct
locations.

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>