qemu: fix regression with spice tls port allocation

In my quest for reusing variables I failed to edit one variable when
fixing details between two patch versions. That results in a failure
to start qemu with autoport and spice tls, because qemu is trying to
bind two sockets to the same port.

src/qemu/qemu_process.c

@@ -3500,7 +3500,7 @@ int qemuProcessStart(virConnectPtr conn,
                     goto cleanup;
                 }
 
-                vm->def->graphics[0]->data.spice.tlsPort = port;
+                vm->def->graphics[0]->data.spice.tlsPort = tlsPort;
             }
         }