e1000: get rid of duplicate exit path

By using goto statement, we can achieve sharing the same exit path so
that code duplication could be minimized.

Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>