radv: Skip tiny non-visible VRAM heap.

When I enable "Above 4G decoding" in my BIOS I still get 16 MiB of
non-visible VRAM on my 8G VRAM GPU ...

CC: mesa-stable
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6827>
1 file changed