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 nvidia: Remove unused variables.

tegra124: Implement new get_gate method for tegra124 clocks.

MFC after: 1 week

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

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

Fixes for NVIDIA Tegra124 clocks:
- EMC clock have standard peripheral clock block. Use it.
- Implement full frequency set method for PLLD2. This PLL
is used as HDMI pixel clock so we must be able to set it
to wide range of frequencies, within 5% tolerance allowed
by HDMI specification. Due to this, full state space search
(over m, n, p fields) is necessary.

MFC after: 3 weeks

TEGRA: Fix numerous issues in clock code.
Define and export clocks related to XUSB driver.

TEGRA: Extend timeout for PLLs lock to 5 ms. Real lock time for PLLA
has been very near to old limit.

TEGRA: Fix CPU frequency switching.
The PLL_X, base CPU frequency source, doesn't have a bypass switch and thus
we must use another frequency source for CPU while changing its frequency.
PLL_P is ideal for this, it runs at 480MHz and CPU can be clocked at this
frequency at any CPU voltage.

Import basic support for Nvidia Jetson TK1 board and tegra124 SoC.
The following pheripherals are supported: UART, MMC, AHCI, EHCI, PCIe, I2C,
PMIC, GPIO, CPU temperature and clock.

Note: The PCIe driver is pure mash at this moment. It will be reworked
immediately when both D5237 and D2579 enter the current tree.