The cleanup in 548babf8 relies on some functions not available in older
ESP-IDF. Temporarily restore them, until we drop support for ESP-IDF <5.2.
PWM functionality should end up the same regardless of ESP-IDF version, and
also no different from MicroPython V1.23.
Signed-off-by: Angus Gratton <angus@redyak.com.au>