Added changes for the BLE callback handler

Author: shgutte

src/platform/silabs/BLEManagerImpl.h

@@ -209,6 +209,12 @@ class BLEManagerImpl final : public BLEManager, private BleLayer, private BlePla
     static void DriveBLEState(intptr_t arg);
     static void BleAdvTimeoutHandler(TimerHandle_t xTimer);
     uint8_t GetTimerHandle(uint8_t connectionHandle, bool allocate);
+
+
+ #if (SLI_SI91X_ENABLE_BLE || RSI_BLE_ENABLE)   
+    protected:
+    static void OnSendIndicationTimeout(System::Layer * aLayer, void * appState);
+#endif
 };
 
 /**