ixgbe: force VF to grab new MAC on driver reload

Do not validate the MAC address during a reset, unless the MAC was set on
the host. This way the VF will get a new MAC address every time it reloads.

Remove the "no MAC address assigned" message since it will get spammed on
reset and it doesn't help much as the MAC on the VF is randomly generated.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>