i40e: Driver prints log message on link speed change

This patch makes the driver log link speed change. Before applying the
patch link messages were printed only on state change. Now message is
printed when link is brought up or down and when speed changes.

Change-ID: Ifbee14b4b16c24967450b3cecac6e8351dcc8f74
Signed-off-by: Filip Sadowski <filip.sadowski@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>