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/comp_decomp/comp_decomp_sync.v

@@ -10,6 +10,7 @@
 
 `include "sync_rtl/common/defines.vh"
 
+(* use_dsp = "no" *)
 module comp_decomp_sync (
     input         clk,
     input         rst_n,