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

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

Fix the SPDX-License-Identifier in DMC-620 files

The SPDX-License-Identifier was wrong in the Arm CoreLink DMC-620
driver files. It used the incorrect FreeBSD variant of the BSD-2-Clause
identifier. According to [1] all files should use BSD-2-Clause.

[1] https://tools.spdx.org/app/check_license/

Reported by: emaste
Sponsored by: Arm Ltd

Allocate event for DMC-620 and CMN-600 controllers PMU. Add events supported by DMC-620 and CMN-600 controllers PMU.

Allocate event for DMC-620 and CMN-600 controllers PMU.
Add events supported by DMC-620 and CMN-600 controllers PMU.

Reviewed by: bz
Sponsored By: ARM
Sponsored By: Ampere Computing
Differential Revision: https://reviews.freebsd.org/D35609