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/

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

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

arm allwinner: Remove unused devclass arguments to DRIVER_MODULE.

aw_gmacclk: Remove unused variables.

Remove "all rights reserved" from copyright for the file that Jared McNeill
own. He gave me permission to do this.

allwinner: Rework the BUS_PASS on drivers

- Put all clock and control unit driver in BUS_PASS_RESOURCE except
for the DE2 CCU as it needs the main CCU to be available.
- Use BUS_PASS_CPU for a20_cpu_cfg as it makes more sense.
- For aw_syscon use SCHEDULER pass as we need it early for drivers
that attach in BUS_PASS_SUPPORTDEV
- For the rest we can use BUS_PASS_SUPPORTDEV

allwinner: clk: Garbage collect old clock implementation

The old clocks are disconneted from the build since r337344.
Remove all those pseudo drivers. The only one remaining is for gmac
(the ethernet controller) so move it to sys/arm/allwinner.
While here remove a83t support from gmacclk as it is unneeded since r326114.

MFC after: 1 month