AP_RPM: correct SITL backend compilation if RPM disabled in SITL

libraries/AP_RPM/RPM_SITL.cpp

@@ -13,12 +13,11 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <AP_HAL/AP_HAL.h>
-
-#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
 #include "RPM_SITL.h"
 
-extern const AP_HAL::HAL& hal;
+#if AP_RPM_SIM_ENABLED
+
+#include <AP_HAL/AP_HAL.h>
 
 /*
    open the sensor in constructor
@@ -46,4 +45,4 @@ void AP_RPM_SITL::update(void)
 
 }
 
-#endif // CONFIG_HAL_BOARD
+#endif // AP_RPM_SIM_ENABLED

libraries/AP_RPM/RPM_SITL.h

@@ -14,9 +14,10 @@
  */
 #pragma once
 
-#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
-
 #include "AP_RPM.h"
+
+#if AP_RPM_SIM_ENABLED
+
 #include "RPM_Backend.h"
 #include <SITL/SITL.h>
 
@@ -33,4 +34,4 @@ private:
     uint8_t instance;
 };
 
-#endif // CONFIG_HAL_BOARD
+#endif // AP_RPM_SIM_ENABLED