e1000e: 82577/82578 requires a different method to configure LPLU

Unlike previous ICHx-based parts, the PCH-based parts (82577/82578) require
LPLU (Low Power Link Up, or "reverse auto-negotiation") to be configured in
the PHY rather than the MAC.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>