fix combinatorial loop in x illegal

rtl/cv32e40px_x_disp.sv

@@ -107,6 +107,7 @@ module cv32e40px_x_disp
   logic x_if_not_ready;
   logic x_if_memory_instr;
   logic illegal_forwarding_prevention;
+  logic x_issue_illegal;
 
   // issue interface
   assign x_issue_valid_o = x_illegal_insn_dec_i & ~branch_or_jump_i & ~instr_offloaded_q & instr_valid_i & ~illegal_forwarding_prevention;
@@ -244,9 +245,10 @@ module cv32e40px_x_disp
   end
 
   // illegal instruction assignment
+  assign x_issue_illegal = x_illegal_insn_dec_i & ~instr_offloaded_q & instr_valid_i;
   always_comb begin
     x_illegal_insn_o = 1'b0;
-    if (x_issue_valid_o & x_issue_ready_i & ~x_issue_resp_accept_i) begin
+    if (x_issue_illegal & x_issue_ready_i & ~x_issue_resp_accept_i) begin
       x_illegal_insn_o = 1'b1;
     end
   end