radv: improve reporting faulty pipelines when a GPU hang is detected

Because the driver now waits for idle after every draw/dispatch
calls, we shouldn't report gfx pipelines when the GPU hang happens
after a dispatch (or the opposite).

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by:  Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6471>