e1000e: cleanup: rename e1000_get_cfg_done()

In keeping with the e1000e driver function naming convention, the subject
function is renamed to indicate it is generic, i.e. it is applicable to
more than just a single MAC family (e.g. 80003es2lan, 82571, ich8lan).

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>