ci/bare-metal: Allow wget of the kernel/dtb for kernel development.

It's useful for kernel dev to be able throw all of our testing
infrastructure at a risky kernel change, but it's expensive (time and
bandwidth) to roll new containers every time your rev your kernel.  Make
it so you can just point the env vars to your personal build you've
uploaded.

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6592>
2 files changed