aco: Use v_fmaak/v_fmamk if two operands are the same literal.

aco: Use v_fmaak/v_fmamk if two operands are the same literal.

Foz-DB Navi21:
Totals from 5744 (4.26% of 134913) affected shaders:
VGPRs: 237128 -> 237056 (-0.03%); split: -0.04%, +0.01%
CodeSize: 16654484 -> 16620668 (-0.20%); split: -0.23%, +0.03%
MaxWaves: 152838 -> 152846 (+0.01%)
Instrs: 3063214 -> 3058572 (-0.15%); split: -0.17%, +0.02%
Latency: 23935195 -> 23934827 (-0.00%); split: -0.03%, +0.03%
InvThroughput: 5478562 -> 5478160 (-0.01%); split: -0.01%, +0.01%
VClause: 60432 -> 60435 (+0.00%); split: -0.02%, +0.03%
SClause: 121032 -> 120896 (-0.11%); split: -0.20%, +0.09%
Copies: 147865 -> 143144 (-3.19%); split: -3.59%, +0.40%
PreSGPRs: 195722 -> 195661 (-0.03%); split: -0.06%, +0.03%
PreVGPRs: 182849 -> 182787 (-0.03%)

Foz-DB Vega10:
Totals from 5290 (3.92% of 135041) affected shaders:
SGPRs: 357952 -> 359616 (+0.46%); split: -0.11%, +0.57%
VGPRs: 204048 -> 203928 (-0.06%); split: -0.08%, +0.02%
CodeSize: 14043176 -> 14003100 (-0.29%); split: -0.29%, +0.00%
MaxWaves: 39401 -> 39398 (-0.01%); split: +0.01%, -0.02%
Instrs: 2636739 -> 2631246 (-0.21%); split: -0.21%, +0.00%
Latency: 25264088 -> 25256482 (-0.03%); split: -0.05%, +0.02%
InvThroughput: 12039643 -> 12039346 (-0.00%); split: -0.00%, +0.00%
VClause: 55603 -> 55584 (-0.03%); split: -0.04%, +0.00%
SClause: 101577 -> 101342 (-0.23%); split: -0.30%, +0.07%
Copies: 213344 -> 207929 (-2.54%); split: -2.58%, +0.05%
Branches: 34053 -> 34054 (+0.00%)
PreSGPRs: 172405 -> 172260 (-0.08%)

Signed-off-by: Georg Lehmann <dadschoorse@gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18645>