HAL_PX4: fixed oneshot125 on non-alt outputs

libraries/AP_HAL_PX4/RCOutput.cpp

@@ -356,11 +356,14 @@ void PX4RCOutput::write(uint8_t ch, uint16_t period_us)
     }
 
     if (_output_mode == MODE_PWM_ONESHOT125) {
+        if (((ch < _servo_count) && ((1U<<ch) & _rate_mask_main)) ||
+            ((ch >= _servo_count) && ((1U<<(ch-_servo_count)) & _rate_mask_alt))) {
             // we treat oneshot125 very simply on HAL_PX4, with 1us
             // resolution. Correctly handling it would use a 125 nsec
             // step size, to give the full 1000 steps
             period_us /= 8;
         }
+    }
 
     // keep unscaled value
     _last_sent[ch] = period_us;