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

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

bwn(4): migrate bwn(4) to the native bhnd(9) interface, and drop siba_bwn.

- Remove the shim interface that allowed bwn(4) to use either siba_bwn or
bhnd(4), replacing all siba_bwn calls with their bhnd(4) bus equivalents.
- Drop the legay, now-unused siba_bwn bus driver.
- Clean up bhnd(4) board flag defines referenced by bwn(4).

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D13518

[bwn] add initial bwn(4) N-PHY code, ported from Linux b43.

This is a GPLv2 PHY-N implementation based on the Linux b43 driver,
ported over to work in bwn(4).

I've tested this on the BCM4321 11abgn device, in 11bg and 11a modes.
The b43 PHY code only supports 11abg, no 11n, and 20MHz only wide
channels.

Yes, this is a GPLv2 driver, so it won't be included in the
default builds.

Tested:

* BCM4321 11abgn device (Apple!), 11bg and 11a STA mode.

Obtained from: Linux b43