AP_Notify: add support for alternate alarm function

enable alarm based on pwm

libraries/AP_Notify/AP_Notify.cpp

@@ -354,7 +354,7 @@ void AP_Notify::add_backends(void)
 // ChibiOS noise makers
 #if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS
     ADD_BACKEND(new Buzzer());
-#if defined(HAL_PWM_ALARM) || HAL_DSHOT_ALARM
+#if HAL_USE_PWM == TRUE || HAL_DSHOT_ALARM
     ADD_BACKEND(new AP_ToneAlarm());
 #endif
 

libraries/AP_Notify/ToneAlarm.cpp

@@ -105,7 +105,7 @@ bool AP_ToneAlarm::init()
     if (pNotify->buzzer_enabled() == false) {
         return false;
     }
-#if ((defined(HAL_PWM_ALARM) || HAL_DSHOT_ALARM) && CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS) || \
+#if ((defined(HAL_PWM_ALARM) || defined(HAL_PWM_ALT_ALARM) || HAL_DSHOT_ALARM) && CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS) || \
     CONFIG_HAL_BOARD == HAL_BOARD_LINUX || \
     CONFIG_HAL_BOARD == HAL_BOARD_SITL
     if (!hal.util->toneAlarm_init(pNotify->get_buzzer_types())) {