cpu/esp_common: use ESP-IDF random API for ESP32

[gschorcht]

Contribution description

This PR is a split-off from PR #17841 and provides the changes to use the ESP-IDF random API for periph/hwrng. This RNG uses the noise in the RF system of the WiFi or the BT interface as entropy source. If neither WiFi nor BT are used, an internal non-RF entropy source is used, the internal reference voltage noise.

Testing procedure

Compile and test

BOARD=esp32-wroom-32 make -j8 -C tests/periph_hwrng/ flash term

Issues/PRs references

Split-off from PR #17841

[benpicco]

Suggested change

	#if defined(MCU_ESP8266) || !defined(ESP32_USE_ESP_IDF_RANDOM)
	#if !IS_USED(ESP32_USE_ESP_IDF_RANDOM)

[benpicco]

Or just split the file between esp32 and esp8266 if that's possible

[gschorcht]

Ok, I can move old implementation to cpu/esp8266 and remove it in cpu/esp32. There is no reason to enable the old implementation for ESP32 because the new implementation is better because it works for all ESP32x SoC variants and gives better entropy. It is easy to split it. May I squash the split directly?

[benpicco]

If you provide a ESP32_USE_ESP_IDF_RANDOM define we might as well use it to allow switching to the 'old' implementation if desired. Since it's already unset for the esp8266 case we don't need to check for it twice.

Apart for the nitpick ACK, just squash directly

[maribu]

The usual false positive due to mismatching checksums of an unrelated build (not even an ESP32 or ESP8266 board)