Don't count vm as an entity in BackupPC's entities discovery

zabbix_scripts/disco_backuppc_sudo

@@ -32,7 +32,7 @@ my $json;
 if ($entities) {
   my %entities = ();
   foreach my $host ( keys %$hosts ){
-    if ($host =~ m/^(?:vm_)?([^_]+)_.*/) {
+    if ( $host =~ m/^(?:vm_)?([^_]+)_.*/ and $1 ne 'vm' ) {
       $entities{$1}= 1;
     }
   }