igc: Complete to commit Add legacy power management support

commit 9513d2a5 ("igc: Add legacy power management support")
Add power management resume and schedule suspend requests.
Add power management get and put synchronization.

Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>