syscon: Move syscon code in dev/syscon

We've removed kernel option EXT_RESOURCES almost two years ago.
While it was ok to have some code under a common 'extres' subdirectory
at first, we now have a lot of consumer of it and we made it mandatory
so no need to have it under a cryptic name.

Reviewed by: mhorne
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D43196

sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

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

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Fix/add compat strings for Rockchip RK356x GRF.

Add support for RK3568 to RockChip GRF and SPI drivers.
Partially from https://reviews.freebsd.org/D36027

Submitted by: sos

arm64 rockchip: Remove unused devclass arguments to DRIVER_MODULE.

Remove "all rights reserved" from copyright for the file I own.
Some of the files have both me and Jared McNeill and he gave me
permission to remove it from his files too.

Add support for RK3288 into existing RockChip drivers.
This patch ensures only minimal level of compatibility necessary to boot
on RK3288 based boards. GPIO and pinctrl interaction, missing in current
implementation, will be improved by own patch in the near future.

MFC after: 2 weeks
MFC with: r351452

Subclass Rockchip's General Register Files driver from Simple MFD driver.

arm64/rockchip: add RK3399 support

Add CRU (Clock and Reset Unit) driver for RK3399.
Add support in rk_pinctrl driver.

Submitted by: Greg V <greg@unrelenting.technology> (Original version)
Differential Revision: https://reviews.freebsd.org/D16732

MFC after: 1 month

arm64: rockchip: Add GRF driver

RockChip GRF (General Register Files) is present on almost all RockChip
SoC and is used to control some area of the system like iomuxing, gpio
or usb phy.
We need it to be probed and attached early in the boot process so
subclass syscon_generic and set the pass to BUS_PASS_BUS + BUS_PASS_ORDER_MIDDLE.