e1000e: ICHx/PCHx LOMs should use LPLU setting in NVM when going to Sx

When going to Sx with an ICHx/PCH device, the default Low Power Link Up
(LPLU, a.k.a. reverse auto-negotiation) behavior should be whatever is set
in the NVM.  However, the function e1000_suspend_workarounds_ich8lan()
called when going to Sx always enabled LPLU in all power states.

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>