e1000: Fix mii-tool access to setting speed and duplex

Paul Rolland reported that e1000 was having a hard time using mii-tool to set speed and duplex.  This patch fixes the issue on both newer hardware as well as fixing the code issue that originally caused the problem.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>