panfrost: Use preuploaded shader descriptors

panfrost: Use preuploaded shader descriptors

For non-fragment shaders, we can just use the preuploaded BO as-is and
do no packing/copying at draw-time. Fragment shaders are still a bit of
an edge case, in having rasterizer/zsa/blend state in the same
descriptor, but now we can specialize that path further for
fragment-only.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6440>