i40e: don't complain about removing non-existent addresses

We don't need to complain in the log about mac addresses that
can't be deleted because they don't exist.

Change-ID: I4e6370df175bf72726f06d2206c03bcbfded8387
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>