[dd, prim] Simplyfing condition to ease coverage closure

The acknoledgement can't be set unless the request is set. The
condition has been simplified to only check for the acknoledgment.

In addition, the new assertion checks if the ack is set, the request
must be set

Signed-off-by: Antonio Martinez Zambrana <[email protected]>

hw/ip/prim/rtl/prim_reg_cdc_arb.sv

@@ -154,7 +154,11 @@ module prim_reg_cdc_arb #(
     always_ff @(posedge clk_dst_i or negedge rst_dst_ni) begin
       if (!rst_dst_ni) begin
         id_q <= SelSwReq;
-      end else if (dst_update_req && dst_update_ack) begin
+      end else if (dst_update_ack) begin
+        // The condition above was originally `dst_update_req && dst_update_ack`.
+        // However, since there can't be an ACK without a REQ that means the condition
+        // can be simplified to `dst_update_ack` only.
+        // Assertion `DstAckReqChk_A` checks the above always happens
         id_q <= SelSwReq;
       end else if (dst_req && dst_lat_d) begin
         id_q <= SelSwReq;
@@ -165,6 +169,10 @@ module prim_reg_cdc_arb #(
       end
     end
 
+    // dst_update_ack should only be sent if there was a dst_update_req.
+    // By association, whenever src_ack is seen, then src_busy must be high.
+    `ASSERT(DstAckReqChk_A, dst_update_ack |-> dst_update_req, clk_dst_i, !rst_dst_ni)
+
     // if a destination update is received when the system is idle and there is no
     // software side request, hw update must be selected.
     `ASSERT(DstUpdateReqCheck_A, ##1 dst_update & !dst_req & !busy |=> id_q == SelHwReq,