Revert "panfrost: Drop implicit blend pooling"

This reverts commit dc7fbe114bac338e7075efdb325053ef41dad91c.

Fixes INSTR_INVALID_PC faults with the SuperTuxKart advanced rendering
pipeline, which occurred when blend shader BOs were allocated far apart.

Fixes: dc7fbe114ba ("panfrost: Drop implicit blend pooling")
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6785>
3 files changed