Fix some static analysis defects.

A few silly errors, a few unlikely errors, a few changes that should
not have resulted in a problem but makes the code clearer.

Change-Id: Id2c82e9317d53822e4da13c94dec9595ea33b07a
Reviewed-by: Ling Hu <ling.hu@nokia.com>
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>

src/multimedia/audio/qaudiodeviceinfo.cpp

@@ -62,7 +62,12 @@ namespace
 class QAudioDeviceInfoPrivate : public QSharedData
 {
 public:
-    QAudioDeviceInfoPrivate():info(0) {}
+    QAudioDeviceInfoPrivate()
+        : info(0),
+          mode(QAudio::AudioOutput)
+    {
+    }
+
     QAudioDeviceInfoPrivate(const QString &r, const QByteArray &h, QAudio::Mode m):
         realm(r), handle(h), mode(m)
     {