ath10k: import ath10k driver

Import ISC-licensed ath10k driver assumed to be
based on Linux kvalo/ath.git master at
6bae9de622d3ef4805aba40e763eb4b0975c4f6d.

Import support to redirect fwlogs to kernel messages
from https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/389075

Complement the driver to make compile on FreeBSD
using LinuxKPI with changes covered by #ifdef (__FreeBSD__).
Further select updates were applied since the initial import
in order to keep compiling along with other LinuxKPI based
drivers.

Any other native driver using BUS_PROBE_DEFAULT will attach
ignoring this one by default given bsd_probe_return is set
to a lower priority.

Add the module build framework.

We only support PCI parts.

The firmware is provided by port net/wifi-firmware-ath10k-kmod.

Given the lack of full license texts on most files this is
imported under the draft policy for handling SPDX files (D29226). [1]

Approved by: core (emaste, 2022-04-08) [1]
MFC after: 2 months