radv,radeonsi: use ac_nir_lower_tex

radv,radeonsi: use ac_nir_lower_tex

fossil-db (navi21):
Totals from 17279 (12.74% of 135636) affected shaders:
MaxWaves: 270015 -> 269991 (-0.01%)
Instrs: 24847385 -> 24843807 (-0.01%); split: -0.02%, +0.00%
CodeSize: 133215364 -> 133198744 (-0.01%); split: -0.02%, +0.01%
VGPRs: 1217632 -> 1217872 (+0.02%); split: -0.00%, +0.02%
Latency: 405347021 -> 404971784 (-0.09%); split: -0.09%, +0.00%
InvThroughput: 75386590 -> 75350344 (-0.05%); split: -0.07%, +0.03%
VClause: 426986 -> 426821 (-0.04%); split: -0.04%, +0.01%
SClause: 966751 -> 966971 (+0.02%); split: -0.01%, +0.03%
Copies: 1738510 -> 1737970 (-0.03%); split: -0.08%, +0.05%
PreSGPRs: 1169070 -> 1169120 (+0.00%); split: -0.00%, +0.00%
PreVGPRs: 1136102 -> 1136183 (+0.01%); split: -0.00%, +0.01%

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22636>