apex: add a driver for the Google Apex Edge TPU

[seuros]

Summary

The Apex is the accelerator on Coral PCI Express and M.2 modules,
appearing as 1ac1:089a
Google's Linux driver left staging in 5.16 and the out of tree
repository was archived; no BSD has had one.

Tested on: amd64, Coral M.2 Accelerator, running MobileNet v1
with the TensorFlow Lite 2.16 and LiteRT runtimes

[seuros]

The USB variant is more common than the PCIE/M2 in the wild, but i did not want to port it without testing it on hardware.

I will check with some frigate or home-assistant friends if they have they can undust the coral .

PS: the linux driver has a bug that will never be fixed (the repo is archived) which pushed people in stopped the coral usage. this port address it.

[seuros]

fix docs

[adrian]

in general good; just update your email address!

sys/dev/apex/apex.c

60

Maybe create a #define for how big this can get instead of '3' and use that for bounds checking the array?

[ziaee]

looks cool; please also relnotes: yes for any new driver

share/man/man4/apex.4

14–27

can also add tunables and sysctls if you want, see share/examples/mdoc/example.4

44

see share/man/man5/style.mdoc.5

[seuros]

refactor/doc/split driver

[seuros]

rebase on main