[core] Conditionally compile get_loop_priority with USE_LOOP_PRIORITY (#14210)

esphome/core/component.cpp

@@ -85,7 +85,9 @@ void store_component_error_message(const Component *component, const char *messa
 static constexpr uint16_t WARN_IF_BLOCKING_INCREMENT_MS =
     10U;  ///< How long the blocking time must be larger to warn again
 
+#ifdef USE_LOOP_PRIORITY
 float Component::get_loop_priority() const { return 0.0f; }
+#endif
 
 float Component::get_setup_priority() const { return setup_priority::DATA; }