fix(rtl): add use_dsp="no" attributes, fix duplicate wire declaration

Add (* use_dsp = "no" *) to all modules containing multiplication
operators to force LUT-based multiplication instead of DSP inference:
- barrett_mul.v (3 multipliers x 7 instances = 21 ops)
- comp_decomp_sync.v, sample_ntt_sync*.v, mlkem_top.v

Also fix duplicate wire declaration of ct_bytes_rt in mlkem_top.v.

sync_rtl/sample_ntt/sample_ntt_sync.v

@@ -31,6 +31,7 @@
 `include "sync_rtl/common/defines.vh"
 
 /* verilator lint_off UNUSEDPARAM */
+(* use_dsp = "no" *)
 module sample_ntt_sync #(parameter K = 4) (
 /* verilator lint_on UNUSEDPARAM */
     input              clk,