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

o) Allow devices to override the MDIO read and write functions presented to
the miibus attached to octe interfaces.
o) Add an SMI/MDIO interface to the MV88E61XX and use it for the switch PHY on
the Lanner MR-320. An actual driver for the switch PHY will come later.
Note that for now it intercepts and fakes MII_BMSR reads to prevent the
miibus from talking to anything but the switch itself.