igb: remove three redundant functions left in the code

Three functions were left in the code that are no longer used.  I am removing
these functions just to keep the code clean.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>