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

Merge in support for PAPR-compliant (Power Architecture Platform
Requirements) systems from the projects/pseries branch. This in principle
includes all IBM POWER hardware released in the last 15 years with the
exception of POWER3-based systems when run in 64-bit mode. The main
development target, however, has been the PAPR logical partition support
that is the default target in KVM on POWER and QEMU -- mileage may vary
on actual hardware at present. Much of the heavy lifting here was done
by Andreas Tobler.

Approved by: re (kib)