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

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

Use named field's initializer when constructing <foo>_platform structure.
In current code, the delay argument in FDT_PLATFORM_DEF(2) improperly
initialize refs field from kobj_class structure instead of delay_count
field.
This causes not working DELAY() function (due to never initialized
delay_count) in earlier boot stages, until the first timer was attached.

MFC after: 2 weeks

Add external PLATFORM access on arm, and use it in the pl310 driver.

This allows multiple instances of SoCs that use the pl310 driver to be
built within the same kernel:

* Add access to the platform_t object from outside platform.c
* Use this with the pl310 driver

There is a new platform_pl310 interface to replace the existing code. SoCs
need to implement the init method, and if they have special requirements to
write to the two registers we care about will also need to implement the
write_ctrl and write_debug methods.

Differential Revision: https://reviews.freebsd.org/D11546

Remove the MULTIDELAY option from arm. It's now enabled when PLATFORM is
enabled.

Remove the need for the delay to be zero when MULTIDELAY is undefined,
it may be useful to only enable this in some configs.

Sponsored by: ABT Systems Ltd

Remove struct platform_data, it was never used.

Sponsored by: ABT Systems Ltd

Add a MULTIDELAY option to allow the ARM kernel to have multiple DELAY
implementations. Early in the boot the kernel will use an approximate,
however after the timer has been probed it will switch to a more accurate
implementation.

Reviewed by: manu
Sponsored by: ABT Systems Ltd
Differential Revision: https://reviews.freebsd.org/D5762

Add FDT_PLATFORM_DEF2 for when there are multiple platforms needing to use
the same platform methods.

Add the start of the ARM platform code. This is based on the PowerPC
platform code, it is expected these will be merged in the future when the
ARM code is more complete.

Until more boards can be tested only use this with the Raspberry Pi and
rrename the functions on the other SoCs.

Reviewed by: ian@