libraries: wrong value for setFrequency() (#6409)
libraries: wrong value for setFrequency() (#6409)

Thanks to fix suggestion from @UlliBien.

Fixes: https://github.com/esp8266/Arduino/issues/6380
sticilface/Arduino,esp8266/Arduino,sticilface/Arduino,sticilface/Arduino,esp8266/Arduino,esp8266/Arduino,esp8266/Arduino,sticilface/Arduino,esp8266/Arduino,sticilface/Arduino