RTC is 32.768kHz thus 512 RtcClk equals 15625 usec. The documentation
likely has dropped precision and that's why the driver mistakenly took
the slightly deviated value.

Cc: stable@vger.kernel.org
Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Suggested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/linux-gpio/2f4706a1-502f-75f0-9596-cc25b4933b6c@redhat.com/
Link: https://lore.kernel.org/r/20201105231912.69527-3-coiby.xu@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>