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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Remove "All Rights Reserved" from FreeBSD Foundation sys/ copyrights

These ones were unambiguous cases where the Foundation was the only
listed copyright holder (in the associated license block).

Sponsored by: The FreeBSD Foundation

bhnd: clean up empty lines in .c and .h files

SPDX: license IDs for some ISC-related files.

bhnd(4): extend the PMU APIs to support bwn(4)

The bwn(4) driver requires a number of extensions to the bhnd(4) PMU
interface to support external configuration of PLLs, LDOs, and other
parameters that require chipset or PHY-specific workarounds.

These changes add support for:

- Writing raw voltage register values to PHY-specific LDO regulator
registers (required by LP-PHY).
- Enabling/disabling PHY-specific LDOs (required by LP-PHY)
- Writing to arbitrary PMU chipctrl registers (required for common PHY PLL
reset support).
- Requesting chipset/PLL-specific spurious signal avoidance modes.
- Querying clock frequency and latency.

Additionally, rather than updating legacy PWRCTL support to conform to the
new PMU interface:

- PWRCTL API is now provided by a bhnd_pwrctl_if.m interface.
- Since PWRCTL is only found in older SSB-based chipsets, translation from
bhnd(4) bus APIs to corresponding PWRCTL operations is now handled
entirely within the siba(4) driver.
- The PWRCTL-specific host bridge clock gating APIs in bhnd_bus_if.m have
been lifted out into a standalone bhnd_pwrctl_hostb_if.m interface.

Approved by: adrian (mentor, implicit)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D12664

bhnd: Implement bhnd(4) platform device registration.

Add bhnd(4) API for explicitly registering BHND platform devices (ChipCommon,
PMU, NVRAM, etc) with the bus, rather than walking the newbus hierarchy to
discover platform devices. These devices are now also refcounted; attempting
to deregister an actively used platform device will return EBUSY.

This resolves a lock ordering incompatibility with bwn(4)'s firmware loading
threads; previously it was necessary to acquire Giant to protect newbus access
when locating and querying the NVRAM device.

Approved by: adrian (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D12392