This commit fixes the issue when trying to allocate memory
with the MALLOC_CAP_EXEC in RTC memory. Prior to the fix,
the heap allocator was returning an address in RTC DRAM.
To fix this issue:
- modified memory_layout.c of the concerned targets to fill the iram_address
field in the rtc entry of the soc_memory_region array properly.
- modified heap component related functions to return IRAM address when
an allocation in RTC memory with MALLOC_CAP_EXEC is requested.
Closes https://github.com/espressif/esp-idf/issues/14835