amd/llvm: switch to 3-spaces style

Follow-up of !4319 using the same clang-format config.

Acked-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Acked-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5310>
10 files changed