Only return distinct Port MAC's and skip '00:00:00:00:00:00' addresses in get_port_macs database query, to reduce the number of rows returned from the database to those we will be able to use

Netdisco/lib/App/Netdisco/Util/PortMAC.pm

@@ -41,8 +41,9 @@ sub get_port_macs {
 
     my $dp_macs
         = schema('netdisco')->resultset('DevicePort')
-        ->search( { mac => { '!=' => undef } },
-        { select => [ 'mac', 'ip' ] } );
+        ->search( { mac => { '!=', [ undef, '00:00:00:00:00:00' ] } },
+        { select => [ 'mac', 'ip' ],
+          group_by => [ 'mac', 'ip' ] } );
     my $dp_cursor = $dp_macs->cursor;
     while ( my @vals = $dp_cursor->next ) {
         $port_macs->{ $vals[0] } = $vals[1];