Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

iwmbtfw(8): Add support for Intel 7260/7265 bluetooth adapter firmwares

To use it comms/iwmbt-firmware port should be updated to 20210315 version.

Submitted by: Philippe Michaud-Boudreault <pitwuu@gmail.com>
Tested by: Helge Oldach <freebsd@oldach.net>
Reviewed by: wulf
PR: 228787
MFC after: 2 weeks

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