intel/fs: Use nir_opt_reassociate_bfi

intel/fs: Use nir_opt_reassociate_bfi

All Skylake and newer Intel platforms had similar results. (Ice Lake shown)
total instructions in shared programs: 19907072 -> 19907054 (<.01%)
instructions in affected programs: 8859 -> 8841 (-0.20%)
helped: 9 / HURT: 0

total cycles in shared programs: 855791238 -> 855779334 (<.01%)
cycles in affected programs: 3308294 -> 3296390 (-0.36%)
helped: 12 / HURT: 13

Broadwell
total instructions in shared programs: 17818231 -> 17817440 (<.01%)
instructions in affected programs: 9887 -> 9096 (-8.00%)
helped: 9 / HURT: 0

total cycles in shared programs: 902970035 -> 902941221 (<.01%)
cycles in affected programs: 2767243 -> 2738429 (-1.04%)
helped: 14 / HURT: 5

total spills in shared programs: 17784 -> 17718 (-0.37%)
spills in affected programs: 318 -> 252 (-20.75%)
helped: 1 / HURT: 0

total fills in shared programs: 25458 -> 24949 (-2.00%)
fills in affected programs: 1346 -> 837 (-37.82%)
helped: 1 / HURT: 0

Haswell
total instructions in shared programs: 16707799 -> 16707586 (<.01%)
instructions in affected programs: 24049 -> 23836 (-0.89%)
helped: 41 / HURT: 0

total cycles in shared programs: 882730648 -> 882723174 (<.01%)
cycles in affected programs: 5096737 -> 5089263 (-0.15%)
helped: 25 / HURT: 12

total spills in shared programs: 14937 -> 14909 (-0.19%)
spills in affected programs: 436 -> 408 (-6.42%)
helped: 4 / HURT: 0

total fills in shared programs: 17569 -> 17529 (-0.23%)
fills in affected programs: 444 -> 404 (-9.01%)
helped: 4 / HURT: 0

No shader-db changes on any older Intel platforms.

All Intel platforms had similar results. (Ice Lake shown)
Totals:
Instrs: 153118594 -> 153117340 (-0.00%); split: -0.00%, +0.00%
Cycles: 15011967556 -> 15011904351 (-0.00%); split: -0.00%, +0.00%
Fill count: 203692 -> 203684 (-0.00%)

Totals from 703 (0.11% of 662496) affected shaders:
Instrs: 192826 -> 191572 (-0.65%); split: -0.65%, +0.00%
Cycles: 29937640 -> 29874435 (-0.21%); split: -0.25%, +0.04%
Fill count: 4146 -> 4138 (-0.19%)

Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19968>