* The RNG reading frequency of 200 KHz has been too high for
C6 and H2 since on these chips the RNG output is combined
with the RTC slow clock which is only 150KHz. Reduced the max
reading frequency via esp_random() from 200KHz to 62.5KHz,
which show best results in tests.
Also updated the bootloader_fill_random() max frequency to the
same value to be in line, even though it was just 83KHz.
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