radv, aco: Round texture array index in NIR.

Foz-DB Navi21:
Totals from 9100 (6.75% of 134913) affected shaders:
VGPRs: 609912 -> 610104 (+0.03%); split: -0.01%, +0.05%
SpillSGPRs: 1459 -> 1489 (+2.06%)
CodeSize: 66705920 -> 66620288 (-0.13%); split: -0.13%, +0.00%
MaxWaves: 148546 -> 148518 (-0.02%); split: +0.00%, -0.02%
Instrs: 12278485 -> 12255821 (-0.18%); split: -0.19%, +0.00%
Latency: 277414916 -> 277261192 (-0.06%); split: -0.08%, +0.02%
InvThroughput: 48431180 -> 48394637 (-0.08%); split: -0.11%, +0.03%
VClause: 250866 -> 251062 (+0.08%); split: -0.04%, +0.11%
SClause: 498377 -> 498173 (-0.04%); split: -0.08%, +0.04%
Copies: 652835 -> 655371 (+0.39%); split: -0.09%, +0.48%
Branches: 284367 -> 284371 (+0.00%); split: -0.00%, +0.00%
PreSGPRs: 498580 -> 498477 (-0.02%)
PreVGPRs: 558436 -> 558709 (+0.05%); split: -0.01%, +0.06%