MFC r305094, r305096-r305097

r305094 by cognet:
Garbage collect bits forgotten in r295267.

r305096 by cognet:
Some old arm ports don't load the kernel at the beginning of the memory,
because the bootloader, ie redboot, won't let them do so, and so used the
memory before the kernel for early memory allocation, such as pagetables,
stacks, etc...
Make a bit of an effort to try to get that memory mapped.

r305097 by cognet:
Nuke obio_bs_tag, it was used before it was initialized, and
arm_base_bs_tag is the same, anyway.

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

Use the base arm bus_space instead of an identical local copy.

trim trailing spaces that have accumulated over the years (these files
served as the basis for too many other platforms).

Add initial IOP342 support.
Thanks to Intel for providing sample hardware.

Approved by: re (blanket)