Fix for I2C RTC nxprtc, broken since 2019

From: UEMURA Tetsuya <t_uemura_at_macome.co.jp>
Date: Wed, 14 Sep 2022 10:24:54 UTC
I've found a timing issue in nxprtc.ko and filed a bug with a patch.
Please someone look into the issue following and hopefully commit the
fix.
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=266093

Thanks in advance.

-- 
Tetsuya Uemura <t_uemura@macome.co.jp>