nv50/ir: clean up saturated values immediately

nv50/ir: clean up saturated values immediately

Since we don't iterate to a fixed point, we can end up in situations
where we have a SAT instruction + a long immediate. This is not legal.
However since it's immediately computable, just run unary straight away
to handle the situation.

Fixes: 24a799ad35a82 ("nv50/ir: fix ConstantFolding with saturation")
Reported-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: mesa-stable@lists.freedesktop.org