aco: fix mad splitting after applying output modifiers

aco: fix mad splitting after applying output modifiers

Previously, this wasn't done because the mad label wasn't passed to the
new definition.

fossil-db (Navi):
Totals from 5770 (4.24% of 135946) affected shaders:
SGPRs: 391920 -> 391872 (-0.01%)
VGPRs: 349084 -> 348424 (-0.19%); split: -0.20%, +0.01%
CodeSize: 34639636 -> 34637496 (-0.01%); split: -0.02%, +0.01%
MaxWaves: 58828 -> 58862 (+0.06%)
Instrs: 6723436 -> 6723297 (-0.00%); split: -0.02%, +0.02%
Cycles: 197594168 -> 197591968 (-0.00%); split: -0.02%, +0.02%

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/6293>