aod: fix flashlight brightness restore

Author: mark9064

src/displayapp/screens/FlashLight.cpp

@@ -17,6 +17,7 @@ namespace {
 FlashLight::FlashLight(System::SystemTask& systemTask, Controllers::BrightnessController& brightnessController)
   : systemTask {systemTask}, brightnessController {brightnessController} {
 
+  previousBrightnessLevel = brightnessController.Level();
   brightnessController.Set(Controllers::BrightnessController::Levels::Low);
 
   flashLight = lv_label_create(lv_scr_act(), nullptr);
@@ -52,6 +53,7 @@ FlashLight::FlashLight(System::SystemTask& systemTask, Controllers::BrightnessCo
 FlashLight::~FlashLight() {
   lv_obj_clean(lv_scr_act());
   lv_obj_set_style_local_bg_color(lv_scr_act(), LV_OBJ_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_BLACK);
+  brightnessController.Set(previousBrightnessLevel);
   systemTask.PushMessage(Pinetime::System::Messages::EnableSleeping);
 }
 

src/displayapp/screens/FlashLight.h

@@ -27,6 +27,7 @@ namespace Pinetime {
         Controllers::BrightnessController& brightnessController;
 
         Controllers::BrightnessController::Levels brightnessLevel = Controllers::BrightnessController::Levels::High;
+        Controllers::BrightnessController::Levels previousBrightnessLevel;
 
         lv_obj_t* flashLight;
         lv_obj_t* backgroundAction;