esp_common: Correctly disable ".bss segment placed in external memory" for ESP32-S2 & ESP32-S3

Support for this feature is still pending.

As reported by https://github.com/espressif/esp-idf/issues/6162

components/esp_common/Kconfig.spiram.common

@@ -92,7 +92,7 @@ config SPIRAM_MALLOC_RESERVE_INTERNAL
 config SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
     bool "Allow .bss segment placed in external memory"
     default n
-    depends on SPIRAM
+    depends on SPIRAM && IDF_TARGET_ESP32 # TODO ESP32-S2 IDFGH-4320, ESP32-S3 IDF-1974
     select ESP_ALLOW_BSS_SEG_EXTERNAL_MEMORY
     help
         If enabled, variables with EXT_RAM_ATTR attribute will be placed in SPIRAM instead of internal DRAM.