was: reset display timer on WAS command endpoint result

With WAS Command Endpoint enabled, if a command endpoint takes long to
respond, the display timer might expire before the response arrives.
Reset the display timer when a response arrives.

Fixes #349.

(cherry picked from commit b5a48f5)

main/was.c

@@ -86,6 +86,8 @@ static void IRAM_ATTR cb_ws_event(const void *arg_evh, const esp_event_base_t *b
                                 lv_label_set_text(lbl_ln5, cJSON_IsTrue(ok) ? "Success!" : "Error");
                             }
                             lvgl_port_unlock();
+                            reset_timer(hdl_display_timer, config_get_int("display_timeout", DEFAULT_DISPLAY_TIMEOUT),
+                                        false);
                         }
                     }
                     goto cleanup;