aco/isel: use upper bound for v_mul_u32_u24
The optimizer can use this.
Foz-DB Navi31:
Totals from 577 (0.73% of 79395) affected shaders:
Instrs: 4209237 -> 4206859 (-0.06%); split: -0.06%, +0.00%
CodeSize: 21511192 -> 21511984 (+0.00%); split: -0.02%, +0.02%
SpillSGPRs: 679 -> 671 (-1.18%)
Latency: 28448559 -> 28443863 (-0.02%); split: -0.04%, +0.03%
InvThroughput: 5221932 -> 5218443 (-0.07%); split: -0.09%, +0.02%
Copies: 297965 -> 298076 (+0.04%); split: -0.01%, +0.05%
VALU: 2385304 -> 2383500 (-0.08%)
SALU: 485553 -> 485533 (-0.00%); split: -0.01%, +0.00%