aco: combine VALU and SALU into various VOP3 instructions

aco: combine VALU and SALU into various VOP3 instructions

shader-db (Navi):
Totals from 2916 (2.28% of 127638) affected shaders:
SGPRs: 184427 -> 184283 (-0.08%); split: -0.10%, +0.02%
VGPRs: 143520 -> 143640 (+0.08%); split: -0.00%, +0.09%
CodeSize: 14913548 -> 14913288 (-0.00%); split: -0.00%, +0.00%
MaxWaves: 26034 -> 26012 (-0.08%)
Instrs: 2935435 -> 2930960 (-0.15%); split: -0.15%, +0.00%

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4667>