aco: don't create v_mov_b32 in v_mul_imm()

We switched to p_parallelcopy for everything else.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5390>

src/amd/compiler/aco_builder_h.py

@@ -372,7 +372,7 @@ public:
    {
       assert(tmp.type() == RegType::vgpr);
       if (imm == 0) {
-         return vop1(aco_opcode::v_mov_b32, dst, Operand(0u));
+         return copy(dst, Operand(0u));
       } else if (imm == 1) {
          return copy(dst, Operand(tmp));
       } else if (util_is_power_of_two_or_zero(imm)) {