igb: Support to enable EEE on all eee_supported devices

Current implementation enables EEE on only i350 device. This patch enables
EEE on all eee_supported devices. Also, configured LPI clock to keep
running before EEE is enabled on i210 and i211 devices.

Signed-off-by: Akeem G. Abodunrin <akeem.g.abodunrin@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>