AP_HAL_PX4: replace board ifdef with feature ifdef

libraries/AP_HAL_PX4/Util.cpp

@@ -73,9 +73,10 @@ bool PX4Util::run_debug_shell(AP_HAL::BetterStream *stream)
  */
 enum PX4Util::safety_state PX4Util::safety_switch_state(void)
 {
-#ifdef CONFIG_ARCH_BOARD_AEROFC_V1
+#if !HAL_HAVE_SAFETY_SWITCH
     return AP_HAL::Util::SAFETY_NONE;
-#else
+#endif
+
     if (_safety_handle == -1) {
         _safety_handle = orb_subscribe(ORB_ID(safety));
     }
@@ -93,7 +94,6 @@ enum PX4Util::safety_state PX4Util::safety_switch_state(void)
         return AP_HAL::Util::SAFETY_ARMED;
     }
     return AP_HAL::Util::SAFETY_DISARMED;
-#endif
 }
 
 void PX4Util::set_system_clock(uint64_t time_utc_usec)