nouveau: Fix out-of-bounds access in AlgebraicOpt

for cases where we calculate the absolute value of the result
of a unary operation

We can remove this problematic check since it's redundant with
the one several lines down.

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15476>

src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp

@@ -1835,9 +1835,6 @@ AlgebraicOpt::handleABS(Instruction *abs)
    if (!sub ||
        !prog->getTarget()->isOpSupported(OP_SAD, abs->dType))
       return;
-   // expect not to have mods yet, if we do, bail
-   if (sub->src(0).mod || sub->src(1).mod)
-      return;
    // hidden conversion ?
    ty = intTypeToSigned(sub->dType);
    if (abs->dType != abs->sType || ty != abs->sType)