ixgbevf: Make sure link status and speed are fetched

A recent change makes it necessary to set get_link_status to ensure that
the driver fetches the correct, refreshed value for link status and speed
when it has changed in the physical function device.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>