QFactoryLoader: remove check-before-use of a directory

Unnecessary. We can't read a directory's entries if it doesn't exist or
isn't a directory.

Change-Id: I5e52dc5b093c43a3b678fffd16b5edce70eb651e
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/corelib/plugin/qfactoryloader.cpp

@@ -170,9 +170,6 @@ inline void QFactoryLoaderPrivate::updateSinglePath(const QString &path)
 
     qCDebug(lcFactoryLoader) << "checking directory path" << path << "...";
 
-    if (!QDir(path).exists(QLatin1String(".")))
-        return;
-
     QStringList plugins = QDir(path).entryList(
 #if defined(Q_OS_WIN)
                 QStringList(QStringLiteral("*.dll")),