GStreamer: fix camerabin state and status changes.

Not all status changes where reported and setting the QCamera
to LoadedState was not actually loading anything.

State and status changes have been refactored.
Camera status is now reported directly by the camera session.
Setting the camera state to LoadedState now sets the camerabin to
GST_STATE_READY, that allows to query for camera capabilities without
having to start the camera (and have a valid viewfinder).

Change-Id: I249b1ad32690679ff34a427410bc709ed3ab461c
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

src/plugins/gstreamer/camerabin/camerabincontrol.h

@@ -56,7 +56,7 @@ public:
     QCamera::State state() const;
     void setState(QCamera::State state);
 
-    QCamera::Status status() const { return m_status; }
+    QCamera::Status status() const;
 
     QCamera::CaptureModes captureMode() const;
     void setCaptureMode(QCamera::CaptureModes mode);
@@ -72,7 +72,6 @@ public slots:
     void setViewfinderColorSpaceConversion(bool enabled);
 
 private slots:
-    void updateStatus();
     void delayedReload();
 
     void handleResourcesGranted();
@@ -86,7 +85,6 @@ private:
 
     CameraBinSession *m_session;
     QCamera::State m_state;
-    QCamera::Status m_status;
     CamerabinResourcePolicy *m_resourcePolicy;
 
     bool m_reloadPending;