fix(esp_system): Handle failures correctly in esp_task_wdt_reconfigure()

- Failures were being masked as function always returned ESP_OK
- In the failure path the spinlock was not unlocked, so interrupts
  became permanently disabled.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

components/esp_system/task_wdt/task_wdt.c

@@ -594,9 +594,9 @@ esp_err_t esp_task_wdt_reconfigure(const esp_task_wdt_config_t *config)
         esp_task_wdt_impl_timer_restart(p_twdt_obj->impl_ctx);
     }
 
-    portEXIT_CRITICAL(&spinlock);
 err:
-    return ESP_OK;
+    portEXIT_CRITICAL(&spinlock);
+    return ret;
 }
 
 esp_err_t esp_task_wdt_stop(void)