e1000e: cleanup: remove e1000_set_d0_lplu_state()

Replace the function e1000_set_d0_lplu_state() with the contents of it
coded in place of the single call to the function.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>