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>

src/multimedia/audio/qaudioformat.h

@@ -73,13 +73,9 @@ public:
 
     bool isValid() const;
 
-    void setFrequency(int frequency);
-    int frequency() const;
     void setSampleRate(int sampleRate);
     int sampleRate() const;
 
-    void setChannels(int channels);
-    int channels() const;
     void setChannelCount(int channelCount);
     int channelCount() const;