soc/rtc: reset another BBPLL related register
soc/rtc: reset another BBPLL related register

Follow-up to b21ffc8a: an additional register needs to be reset.

Ref. https://github.com/espressif/esp-idf/issues/2711

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf