[Bug] Incorrect use_vs1 assertion for VWXUNARY0 instructions (vmv.x.s) causing false hazard detection

[yong-shengLiu]

Detailed Description:
In the OPMVV decoding block (ara_dispatcher.sv), the signal ara_req.use_vs1 is set to 1'b1 by default. However, for VWXUNARY0 instructions (specifically vmv.x.s, vcpop, and vfirst), the vs1 source register is not actually used.

Suggested Code Change in ara_dispatcher.sv:

unique case (insn.varith_type.func6)
// ...
6'b010000: begin // VWXUNARY0
// vmv.x.s
// Stall the interface until we get the result
acc_resp_o.req_ready = 1'b0;
acc_resp_o.resp_valid = 1'b0;

  // FIX: These instructions do not use vs1
  ara_req.use_vs1 = 1'b0; 

  case (insn.varith_type.rs1)
    // ...