WiP - Talos II - Add tg3 ethernet driver to be useable under Heads

[tlaurion]

Local build pushed to talos gives:

~ # network-init-recovery 
New value of PCR[5]: 59538b649bbef7d85eabdc0125eba7bb7b6efa6d
insmod: can't insert '/lib/modules/tg3.ko': unknown symbol in module, or unknown parameter
/lib/modules/tg3.ko: insmod failed

Something seems fishy with local buildsystem.
When compiling coreboot:

make -C "/home/user/heads/build/ppc64/coreboot-git" CPUS=2 "crossgcc-ppc64"
make[1]: Entering directory '/home/user/heads/build/ppc64/coreboot-git'
make[3]: powerpc64-linux-gnu-gcc: No such file or directory

Where 47bd80a also doesn't prevent coreboot's buildstack to be rebuilt on each board's build... Will edit this PR later and put as draft for now. Goal is to have CircleCI roms to test and have discussions on CircleCI produced logs on clean build (modules changed by this PR, which will make CircleCI reuse musl-cross-make+coreboot buildstack cache reused and build everything else from scratch).

---

This is #1313 rabased on master now including merged #1362 with added tg3 ethernet modules build requirements.

[tlaurion]

Build happening at https://app.circleci.com/pipelines/github/tlaurion/heads/1583/workflows/13322243-46ba-4ead-9bbd-034a4a06bcd3 for a33cc67

(Why there is no CircleCI output here is unknown, seems like Github and CircleCI still have communication issues. Earlier today, CircleCI was unable to download Github tarballs again, just like last week).

Edit: now github+circleCI communicated. Delay of like 10 minutes. Weird, but not surprising.

[tlaurion]

t3g seems to have external dependencies, module doesn't load. Will get back into this later, wanted a quick way to just have Heads download CircleCI tgz archive to flash internally from now on to further test things with user keyring and user settings (debug enablement) following instead of the added multiple steps needed to flash from bmc and then inject public key and user.config overrides... Later.

Trace: goal was to add NetXtreme BCM5719 Gigabit Ethernet so that network-init could obtain dhcp and then wget single file to be flashed by flash.sh pointing to it. More work to finish this then to continue manual tests for the moment, will get back at this when 20% 80% ratio is on.

[tlaurion]

Where 47bd80a also doesn't prevent coreboot's buildstack to be rebuilt on each board's build...

This is new for 4.17+
Its not .xcompile anymore, and not put in coreboot dir root, unless we specify ourselves to put it there. Not its under objdir by default unless overriden.

[tlaurion]

t3g seems to have external dependencies, module doesn't load

Firmware is missing under Heads kernel for the driver to succeed.