e1000e: Return 1 instead of a non-zero value for link up indication

A number of users have mentioned they have tools that rely on a link-up
indication having a return value of 1 rather than a non-zero value.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>