Remove $FreeBSD$: two-line .h pattern

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

iwmbtfw: Firmware loader for Intel Wireless 8260 based Bluetooth USB devices

Currently supported models are: 8260, 8265, 9560, 9260 and 22161.
Firmware files can be installed with comms/iwmbt-firmware port.

PR: 237083
Reviewed by: hps, emax
X-MFC with: r351196
Differential Revision: https://reviews.freebsd.org/D21071