i40e: Don't exit link event early if link speed has changed

i40e: Don't exit link event early if link speed has changed

Previously we were only checking if the link up state had changed,
and if it hadn't exiting the link event routine early. We should
also check if speed has changed, and if it has, stay and finish
processing the link event.

Change-ID: I9c8e0991b3f0279108a7858898c3c5ce0a9856b8
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>