aco: use storage_scratch

fossil-db (Navi):
Totals from 9 (0.01% of 114665) affected shaders:
VMEM: 14456 -> 15312 (+5.92%)
VClause: 336 -> 327 (-2.68%)

Helps 9 Dark Souls 3 shaders a little.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4905>
1 file changed