AP_Compass: support ChibiOS FMUv4

libraries/AP_Compass/AP_Compass.cpp

@@ -534,7 +534,7 @@ void Compass::_detect_backends(void)
         return;
     }
 
-#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
+#if AP_FEATURE_BOARD_DETECT
     if (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXHAWK2) {
         // default to disabling LIS3MDL on pixhawk2 due to hardware issue
         _driver_type_mask.set_default(1U<<DRIVER_LIS3MDL);
@@ -560,7 +560,7 @@ void Compass::_detect_backends(void)
     
 #if HAL_COMPASS_DEFAULT == HAL_COMPASS_HIL
     ADD_BACKEND(DRIVER_SITL, AP_Compass_HIL::detect(*this), nullptr, false);
-#elif HAL_COMPASS_DEFAULT == HAL_COMPASS_PX4 || HAL_COMPASS_DEFAULT == HAL_COMPASS_VRBRAIN || defined(HAL_CHIBIOS_ARCH_FMUV3)
+#elif AP_FEATURE_BOARD_DETECT
     switch (AP_BoardConfig::get_board_type()) {
     case AP_BoardConfig::PX4_BOARD_PX4V1:
     case AP_BoardConfig::PX4_BOARD_PIXHAWK: