panfrost: Add method to get size of AFBC superblocks valid data

panfrost: Add method to get size of AFBC superblocks valid data

The compute shader is going through all the AFBC header blocks and
calculating the size of valid data by summing up the subblock
sizes (and taking into account solid color, uncompressed mode and
copy blocks). The result is written into the given buffer (array
of `pan_afbc_block_info`).

The size is rounded up to the alignment parameter directly in the
shader.

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25012>