Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix the deciKelvin to Celsius conversion in kernel.

After r285994, sysctl(8) was fixed to use 273.15 instead of 273.20 as 0C
reference and as result, the temperature read in sysctl(8) now exibits a
+0.1C difference.

This commit fix the kernel references to match the reference value used in
sysctl(8) after r285994.

Sponsored by: Rubicon Communications (Netgate)

Improve error handling in smusat(4).

MFC after: 4 days

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

This means that their use is restricted to a single C file.

Add the next digit of precision to temperatures, which I missed when
converting the reporting format from degrees C to 0.1 degree K.

Adapt smusat(4) to use powermac_thermal. This provides automatic fan
management on dual- and quad-core Powermac G5s, and the last G5 iMacs.

Add a driver for the CPU temperature sensors attached over I2C on the
PowerMac 11,2.