add atoms3r backlight iot support (#279)

* add atoms3r backlight iot support

* fix no backlight on error page

main/boards/atoms3-echo-base/atoms3_echo_base.cc

@@ -110,6 +110,7 @@ private:
         InitializeSpi();
         InitializeGc9107Display();
         InitializeButtons();
+        GetBacklight()->SetBrightness(100);
         display_->SetStatus(Lang::Strings::ERROR);
         display_->SetEmotion("sad");
         display_->SetChatMessage("system", "Echo Base\nnot connected");