We had assumed AFBC superblocks were always tiled in an 8x8 pattern,
but this is true only for 32bpp and lower formats; for larger formats
the pattern is 4x4. This isn't an issue yet, but will be when we
support R16G16B16A16 in AFBC.
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35771>