nir/algebraic: Move the flrp -> bcsel rule earlier

nir/algebraic: Move the flrp -> bcsel rule earlier

If multiple rules could match, the rule that appears first in the file
is used.

Only Tiger Lake and Ice Lake are affected.  Other platforms either have
a LRP instruction or can't run any shaders from shader-db that would
benefit.

v2: Fix issues created when this commit was rebased on top of
3c8934a644b8 ("nir/algebraic: add flrp patterns for 16 and 64 bits").
Noticed by Caio.

Tiger Lake and Ice Lake had similar results.
total instructions in shared programs: 20908672 -> 20908661 (<.01%)
instructions in affected programs: 419 -> 408 (-2.63%)
helped: 5
HURT: 0
helped stats (abs) min: 1 max: 3 x̄: 2.20 x̃: 3
helped stats (rel) min: 1.85% max: 3.19% x̄: 2.49% x̃: 2.65%
95% mean confidence interval for instructions value: -3.56 -0.84
95% mean confidence interval for instructions %-change: -3.24% -1.73%
Instructions are helped.

total cycles in shared programs: 473513940 -> 473513793 (<.01%)
cycles in affected programs: 7176 -> 7029 (-2.05%)
helped: 12
HURT: 0
helped stats (abs) min: 5 max: 22 x̄: 12.25 x̃: 12
helped stats (rel) min: 0.84% max: 3.24% x̄: 2.09% x̃: 1.80%
95% mean confidence interval for cycles value: -15.43 -9.07
95% mean confidence interval for cycles %-change: -2.57% -1.61%
Cycles are helped.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6358>