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

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

arm/arm64 nvidia: Remove unused devclass arguments to DRIVER_MODULE.

ARM: Enhance common Nvidia Tegra drivers by support for Tegra210 SoC.

MFC after: 4 weeks

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

TEGRA: Add basic driver for memory controller.
For now, it only reports memory and SMMU access errors.