AP_Frsky_Telem: use serialmanager singleton

libraries/AP_Frsky_Telem/AP_Frsky_Telem.cpp

@@ -41,10 +41,11 @@ AP_Frsky_Telem::AP_Frsky_Telem(AP_AHRS &ahrs, const AP_BattMonitor &battery, con
 /*
  * init - perform required initialisation
  */
-void AP_Frsky_Telem::init(const AP_SerialManager &serial_manager,
-                          const uint8_t mav_type,
+void AP_Frsky_Telem::init(const uint8_t mav_type,
                           const uint32_t *ap_valuep)
 {
+    const AP_SerialManager &serial_manager = AP::serialmanager();
+
     // check for protocol configured for a serial port - only the first serial port with one of these protocols will then run (cannot have FrSky on multiple serial ports)
     if ((_port = serial_manager.find_serial(AP_SerialManager::SerialProtocol_FrSky_D, 0))) {
         _protocol = AP_SerialManager::SerialProtocol_FrSky_D; // FrSky D protocol (D-receivers)

libraries/AP_Frsky_Telem/AP_Frsky_Telem.h

@@ -123,8 +123,7 @@ public:
     AP_Frsky_Telem &operator=(const AP_Frsky_Telem&) = delete;
 
     // init - perform required initialisation
-    void init(const AP_SerialManager &serial_manager,
-              const uint8_t mav_type,
+    void init(const uint8_t mav_type,
               const uint32_t *ap_valuep = nullptr);
 
     // add statustext message to FrSky lib message queue