Delete obsolete class methods and update related code

Delete obsolete methods from QAudioFormat and QAudioDeviceInfo
and update code that relied on the obsolete methods.

Change-Id: I007e36375a45399b1d5a289341bc5d5a05dc68cc
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

examples/audiodevices/audiodevices.h

@@ -68,7 +68,7 @@ public:
 private slots:
     void modeChanged(int idx);
     void deviceChanged(int idx);
-    void freqChanged(int idx);
+    void sampleRateChanged(int idx);
     void channelChanged(int idx);
     void codecChanged(int idx);
     void sampleSizeChanged(int idx);