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: arm64: Directly use #include <dt-binding/...>

We have it in the includes path and this will help the transition to the
new device-tree import in sys/contrib

Align OF_getencprop_alloc API with OF_getencprop and OF_getprop_alloc

Change OF_getencprop_alloc semantics to be combination of malloc and
OF_getencprop and return size of the property, not number of elements
allocated.

For the use cases where number of elements is preferred introduce
OF_getencprop_alloc_multi helper function that copies semantics
of OF_getencprop_alloc prior to this change.

This is to make OF_getencprop_alloc and OF_getencprop_alloc_multi
function signatures consistent with OF_getencprop_alloc and
OF_getencprop_alloc_multi.

Functionality-wise this patch is mostly rename of OF_getencprop_alloc
to OF_getencprop_alloc_multi except two calls in ofw_bus_setup_iinfo
where 1 was used as a block size.

Implement drivers for NVIDIA tegra124 display controller, HDMI source
and host1x module. Unfortunately, tegra124 SoC doesn't have 2D acceleration
engine and 3D requires not yet started nouveau driver.

These drivers forms a first non-x86 DRM2 enabled graphic stack.

Note, there are 2 outstanding issues:
- The code uses gross hack in order to be comply with
OBJT_MGTDEVICE pager. (See tegra_bo_init_pager() in tegra_bo.c)
- Due to improper(probably) refcounting in drm_gem_mmap_single()
(in drm_gem.c), the gem objects are never released.
I hope that I will be able to address both issues in finite time,
but I don't want to touch x86 world now.

MFC after: 1 month