aco: don't emit parallelcopy when switching to WQM.

aco: don't emit parallelcopy when switching to WQM.

The reason was an RA bug which has been fixed a while ago.
This change fixes some register demand miscalculations.

Totals from 1013 (0.73% of 139391) affected shaders (NAVI10):
CodeSize: 6050408 -> 6047504 (-0.05%); split: -0.05%, +0.00%
Instrs: 1160533 -> 1159765 (-0.07%); split: -0.07%, +0.00%
Cycles: 8027212 -> 8024140 (-0.04%); split: -0.04%, +0.00%
VMEM: 296195 -> 296091 (-0.04%)
SMEM: 73003 -> 73011 (+0.01%); split: +0.05%, -0.04%
SClause: 37221 -> 37222 (+0.00%)
Copies: 70931 -> 70166 (-1.08%)

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7903>