sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

SPDX: license IDs for some ISC-related files.

Add the 11n chipset RF frontends to the linker set, even though they're not
attached this way.

The AR5212 based NICs have a variety of RF frontends, so there's a linker set
which the AR5212 attach routine calls. The same framework is used for the
AR5416 and later but as there's a fixed RF frontend for each 11n NIC, it
is just directly attached.

However in the case of compiling a cut down HAL (eg _just_ AR9130 WMAC support),
the linker set ends up being empty and this causes the compile to fail.

So this is just a workaround for that - it means those users who wish an 11n
only HAL can compile the 11n chipsets and RF frontend they need, and just
"ath_ar5212" for the AR5212/AR5416 common code, and it'll just work.

Sponsored by: Hobnob, Inc.

Fix a macro name - it's currently unused in this file however, but
keep it consistent with ar9280.c.

Bring over my AR9287 work in progress.

It isn't linked into the build because it's missing the TX power
and PDADC programming code.

This code is mostly based on the ath9k codebase, compared against
the Atheros codebase as appropriate.

What's implemented:

* probe/attach
* EEPROM board value programming
* RX initial calibration
* radio channel programming
* general MAC / baseband setup
* async fifo setup
* open-loop tx power calibration

What's missing before it can be enabled by default:

* TX power / calibration setting code
* closed-loop tx power calibration routines
* TSF2 handling
* generic timer support from ath9k

Obtained from: Atheros, ath9k