e1000e: Fix wrong comment related to link detection

Reading e1000e_check_for_copper_link() shows that get_link_status is set to
false after link has been detected. Therefore, it stays TRUE until then.

Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>