panfrost: Drop hand-rolled pandecode for attribute buffers

Sadly, we lose some of the validation, but indeed, much of the
validation has turend out to be wrong after enough development so... meh

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/6326>
1 file changed