nir/algebraic: Partially revert 3f782cdd25

I'm not sure what the logic was, but there is no opportunity for
anything to flush to zero here.  'a' is a Boolean value, and b2f
produces 1.0 or 0.0.

This was originally part of
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3765/.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Cc: Andres Gomez <agomez@igalia.com>
Cc: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Cc: Connor Abbott <cwabbott0@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8910>

src/compiler/nir/nir_opt_algebraic.py

@@ -466,7 +466,7 @@ optimizations.extend([
    (('ine', ('iadd', a, b), a), ('ine', b, 0)),
 
    (('feq', ('b2f', 'a@1'), 0.0), ('inot', a)),
-   (('~fneu', ('b2f', 'a@1'), 0.0), a),
+   (('fneu', ('b2f', 'a@1'), 0.0), a),
    (('ieq', ('b2i', 'a@1'), 0),   ('inot', a)),
    (('ine', ('b2i', 'a@1'), 0),   a),