e1000e: disable gig speed when in S0->Sx transition

Most of this workaround is necessary for all ICHx/PCH parts so one of
the two MAC-type checks can be removed.

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