i40e: Move the saving of old link info from handle_link_event to link_event

The watchdog only calls link_event not handle_link_event which means
that we need to save the old information in link_event.

Previously when polling we were comparing current data to the old data
saved the last time we actually received a link event. This means that
the polling would only fix link status changes in one direction
depending on what the last old data saved off was.

Change-ID: Ie590f30fdbcb133d0ddad4e07e3eb1aad58255b3
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>