jedec_ts(4) uses a sysctl format specifier of "IK4", to indicate that it
reports milliKelvin. However, sysctl(8) on stable/10 only knows about "IK",
without a numeric suffix, which represents deciKelvin.

Adjust the format specifier, and round the temperature value reported.

Reviewed by: avg
Sponsored by: Panasas
Differential Revision: https://reviews.freebsd.org/D14055