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

Remove the AR9285 specific structure for LNA diversity and use the HAL.

The AR9300 HAL update included the LNA diversity configuration information
so it can be used in the AR9485 configuration code.

Disable diversity combining support until I can get a firm answer
from Atheros as to what/when this is supposed to be enabled.

Using the default RX fast diversity settings seems to help quite
a bit.

Whilst I'm here, change the prototype to return HAL_BOOL rather than int.

Add the initial AR9285 PHY glue for supporting antenna diversity.
This code isn't currently used anywhere; it's just linked into the build.