RadioComponentController: Add missing const in member functions

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

src/AutoPilotPlugins/Common/RadioComponentController.cc

@@ -897,7 +897,7 @@ void RadioComponentController::_setHelpImage(const char* imageFile)
     emit imageHelpChanged(file);
 }
 
-int RadioComponentController::channelCount(void)
+int RadioComponentController::channelCount(void) const
 {
     return _chanCount;
 }

src/AutoPilotPlugins/Common/RadioComponentController.h

@@ -98,9 +98,9 @@ public:
     bool yawChannelReversed(void);
     bool throttleChannelReversed(void);
 
-    int channelCount(void);
+    int channelCount(void) const;
 
-    int transmitterMode(void) { return _transmitterMode; }
+    int transmitterMode(void) const{ return _transmitterMode; }
     void setTransmitterMode(int mode);
 
 signals: