clk: Move clock code in dev/clk

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/D43191

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/

arm allwinner: Remove unused devclass arguments to DRIVER_MODULE.

arm: allwinner: a10_timer: Plug set but not used variable

Sponsored by: Beckhoff Automation GmbH & Co. KG

arm: allwinner: a23 timer functions are only used for arm64

A bit of code hygiene (no functional changes).

Hide unused code under #ifdef notyet (in one case the only caller is under
that same ifdef), or if it is arm (not arm64) specific code under the
__arm__ ifdef to not yield -Wunused-function warnings during the arm64
kernel compile.

MFC after: 2 weeks

a10_timer: Update the driver so we can use it on other SoC

a10_timer is currently use in UP allwinner SoC (A10 and A13).
Those don't have the generic arm timer.
The arm generic timecounter is broken in the A64 SoC, some attempts have
been made to fix the glitch but users still reported some minor ones.
Since the A64 (and all Allwinner SoC) still have this timer controller, rework
the driver so we can use it in any SoC.
Since it doesn't have the 64 bits counter on all SoC, use one of the
generic 32 bits counter as the timecounter source.

PR: 229644

Rename timer.c to a10_timer.c

Requested by: andrew