aco: propagate SGPRs into VOP1 instructions early.

aco: propagate SGPRs into VOP1 instructions early.

This helps DCE. We should reconsider our optimization order
or maybe do the dead code analysis twice

Totals from 106 (0.08% of 136546) affected shaders (RAVEN):
SGPRs: 7184 -> 7152 (-0.45%)
CodeSize: 736912 -> 736052 (-0.12%)
Instrs: 145739 -> 145509 (-0.16%)
Cycles: 2085344 -> 2084268 (-0.05%)
VMEM: 14819 -> 14807 (-0.08%)
SMEM: 7109 -> 7100 (-0.13%); split: +0.04%, -0.17%
SClause: 5383 -> 5385 (+0.04%)
Copies: 13290 -> 13189 (-0.76%)
PreSGPRs: 5265 -> 5221 (-0.84%)

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6777>