radv: use fix_derivs_in_divergent_cf

radv: use fix_derivs_in_divergent_cf

fossil-db (navi21):
Totals from 3256 (2.40% of 135636) affected shaders:
MaxWaves: 65430 -> 64366 (-1.63%)
Instrs: 3517336 -> 3517724 (+0.01%); split: -0.12%, +0.13%
CodeSize: 18963788 -> 18946904 (-0.09%); split: -0.14%, +0.05%
VGPRs: 172464 -> 175872 (+1.98%); split: -0.02%, +2.00%
Latency: 33643792 -> 33643179 (-0.00%); split: -0.12%, +0.12%
InvThroughput: 5912965 -> 5934404 (+0.36%); split: -0.09%, +0.46%
VClause: 60268 -> 60275 (+0.01%); split: -0.12%, +0.13%
SClause: 125227 -> 125241 (+0.01%); split: -0.09%, +0.10%
Copies: 253452 -> 254638 (+0.47%); split: -1.29%, +1.76%
Branches: 100951 -> 100953 (+0.00%); split: -0.00%, +0.00%
PreSGPRs: 186403 -> 185641 (-0.41%)
PreVGPRs: 153751 -> 156915 (+2.06%); split: -0.06%, +2.12%

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>