esp32: fix regression introduced in automatic light sleep pm

Closes: https://github.com/espressif/esp-idf/issues/2459

Signed-off-by: Mahavir Jain <mahavir@espressif.com>

components/esp32/pm_impl.h

@@ -104,6 +104,10 @@ void esp_pm_impl_isr_hook();
  */
 void esp_pm_impl_dump_stats(FILE* out);
 
+/**
+ * @brief Hook function implementing `waiti` instruction, should be invoked from idle task context
+ */
+void esp_pm_impl_waiti();
 
 #ifdef CONFIG_PM_PROFILING
 #define WITH_PROFILING