wayland: fix check for creating input method connection

Previously code was if socket fd is greater then 0, then we start
process, but new code in 05ebe676d2 reversed logic. So this
made it not start input method at all.

main_wayland.cpp

@@ -254,7 +254,7 @@ void ApplicationWayland::startInputMethod(const QString &executable)
 
     const QString program = arguments.takeFirst();
     int socket = dup(waylandServer()->createInputMethodConnection());
-    if (socket >= 0) {
+    if (socket < 0) {
         qWarning("Failed to create the input method connection");
         return;
     }