simplewallet.unspent_outputs: fix wrong logic for parsing

src/simplewallet/simplewallet.cpp

@@ -6167,7 +6167,7 @@ bool simple_wallet::unspent_outputs(const std::vector<std::string> &args_)
   auto local_args = args_;
 
   std::set<uint32_t> subaddr_indices;
-  if (local_args.size() > 0 && local_args[0].substr(0, 6) != "index=")
+  if (local_args.size() > 0 && local_args[0].substr(0, 6) == "index=")
   {
     if (!parse_subaddress_indices(local_args[0], subaddr_indices))
       return true;