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

Check error return from reading integer part of temperature.

There's a very remote, but possible, chance that the integer part read will
fail, but the fraction read succeeds, at which point the reported temperature is
invalid.

Reported by: Matthew Rezny
MFC after: 3 weeks

Fix some integer signs. These unsigned integers should all be signed.

Found by: clang (powerpc64)

Avoid using the degree symbol. Looks ugly on the console.

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

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

- Improve error handling.
- Add a retry loop for the i2c sensor reading.
- Check on busy status of the chip and on invalid values.
- Fix a typo in a comment.
- Replace the constant 2732 with the ZERO_C_TO_K macro.

Approved by: nwhitehorn (mentor)

Move the celsius-to-kelvin conversion to a place that powermac_thermal can
see it as well.

Update the I2C-based temperature/fan drivers to connect to the Powermac
thermal control module. This provides automatic fan management on all G5
PowerMacs and Xserves.

Remove unused variable. Spotted by a cppcheck
(devel/cppcheck, http://sourceforge.net/projects/cppcheck) run.

Approved by: nwhitehorn (mentor)

Add three new drivers for fan control and temperature reading on the
PowerMac7,2.

- The fcu driver lets us read and write the fan RPMs for all fans in the
PowerMac7,2. This driver is PowerMac specific.
- The ds1775 is a driver to read the temperature for the drive bay sensor.
- The max6690 is another driver to read temperatures. Here it is used to
read the inlet, the backside and the U3 heatsink temperature.

An additional driver, the ad7417, will follow later.

Thanks to nwhitehorn for guiding me through this driver development.

Approved by: nwhitehorn (mentor)