freertos: Force UNICORE mode on ESP32S2

components/freertos/Kconfig

@@ -1,9 +1,15 @@
 menu "FreeRTOS"
 
-    # This is actually also handled in the ESP32 startup code, not only in FreeRTOS.
+    config FREERTOS_SINGLE_CORE_ONLY
+        # invisible config item to always select FREERTOS_UNICORE on single core IDF_TARGET
+        bool
+        default y
+        depends on IDF_TARGET_ESP32S2BETA
+        select FREERTOS_UNICORE
+
     config FREERTOS_UNICORE
+        # This config variable is also checked in the ESP32 startup code, not only in FreeRTOS.
         bool "Run FreeRTOS only on first core"
-        default y if IDF_TARGET_ESP32S2BETA
         default n
         help
             This version of FreeRTOS normally takes control of all cores of