1. move startup_stack attr from soc_memory_type_desc_t to soc_memory_region_t and
remove unused aliased_iram field
2. all of the last level of RAM is retention dma accessible on esp32c3
3. remove esp32c2 and later chips retention dma accessible memory caps
4. allow allocate memory from RTC_RAM with MALLOC_CAP_EXEC cap
The commit fixes the case:
If variables in RTC RAM have been moved around by the linker,
they will be filled with garbage data. Any reset other than OTA would work fine
because the variables would still be initialized from the initial bootup.
So now system time will be valid even after OTA.
Closes https://github.com/espressif/esp-idf/issues/9448
