70_STV: fix of using more than one NIC without assigned IP

git-svn-id: svn://svn.code.sf.net/p/fhem/code/trunk@10587 2b470e98-0d58-463d-a4d8-8e2adae1ed80

fhem/FHEM/70_STV.pm

@@ -86,6 +86,7 @@ sub getMAC4IP($)
   my $IP = shift;
   my @interfaces = IO::Interface::Simple->interfaces;
   foreach my $if (@interfaces) {
+    next unless defined ($if->address);
     if ($if->address eq $IP) {
         return $if->hwaddr;
     }