AP_Notify: make all semaphores recursive

the cost is very similar and this prevents an easy coding error which
can occur on less used code paths

libraries/AP_Notify/NeoPixel.h

@@ -43,5 +43,5 @@ private:
     // periodic callback
     void timer();
     
-    HAL_Semaphore_Recursive _sem;
+    HAL_Semaphore _sem;
 };

libraries/AP_Notify/OreoLED_I2C.h

@@ -179,7 +179,7 @@ private:
 
     // private members
     uint8_t _bus;
-    HAL_Semaphore_Recursive _sem;
+    HAL_Semaphore _sem;
     AP_HAL::OwnPtr<AP_HAL::I2CDevice> _dev;
     bool    _send_required;                         // true when we need to send an update to at least one led
     oreo_state _state_desired[OREOLED_NUM_LEDS];    // desired state