[dv] Fix race condition in ibex_mem_intf_agent

Previous code working with clocking blocks synced to the raw clock
event. Instead they should sync to the clocking block event. This
ensures the values being read are the latest values rather than a cycle
old.

In particular for ibex_mem_intf_agent this meant it was unable to
produce a single cycle response to any memory transaction. With this fix
these are now observed.

dv/uvm/core_ibex/common/ibex_mem_intf_agent/ibex_mem_intf_monitor.sv

@@ -54,7 +54,7 @@ class ibex_mem_intf_monitor extends uvm_monitor;
     ibex_mem_intf_seq_item trans_collected;
     forever begin
       trans_collected = ibex_mem_intf_seq_item::type_id::create("trans_collected");
-      while(!(vif.monitor_cb.request && vif.monitor_cb.grant)) vif.wait_clks(1);
+      while(!(vif.monitor_cb.request && vif.monitor_cb.grant)) @(vif.monitor_cb);
       trans_collected.addr              = vif.monitor_cb.addr;
       trans_collected.be                = vif.monitor_cb.be;
       trans_collected.misaligned_first  = vif.monitor_cb.misaligned_first;
@@ -71,7 +71,7 @@ class ibex_mem_intf_monitor extends uvm_monitor;
       addr_ph_port.write(trans_collected);
       `uvm_info(get_full_name(),"Send through addr_ph_port", UVM_HIGH)
       collect_response_queue.put(trans_collected);
-      vif.wait_clks(1);
+      @(vif.monitor_cb);
     end
   endtask : collect_address_phase
 
@@ -80,7 +80,7 @@ class ibex_mem_intf_monitor extends uvm_monitor;
     forever begin
       collect_response_queue.get(trans_collected);
       do
-        vif.wait_clks(1);
+        @(vif.monitor_cb);
       while(vif.monitor_cb.rvalid === 0);
 
       if (trans_collected.read_write == READ) begin

dv/uvm/core_ibex/common/ibex_mem_intf_agent/ibex_mem_intf_response_driver.sv

@@ -66,7 +66,7 @@ class ibex_mem_intf_response_driver extends uvm_driver #(ibex_mem_intf_seq_item)
       begin
         forever begin
           ibex_mem_intf_seq_item req, req_c;
-          cfg.vif.wait_clks(1);
+          @(cfg.vif.response_driver_cb);
           seq_item_port.get_next_item(req);
           $cast(req_c, req.clone());
           if(~cfg.vif.response_driver_cb.reset) begin
@@ -112,14 +112,18 @@ class ibex_mem_intf_response_driver extends uvm_driver #(ibex_mem_intf_seq_item)
   virtual protected task send_read_data();
     ibex_mem_intf_seq_item tr;
     forever begin
-      cfg.vif.wait_clks(1);
+      @(cfg.vif.response_driver_cb);
       cfg.vif.response_driver_cb.rvalid <=  1'b0;
       cfg.vif.response_driver_cb.rdata  <= 'x;
       cfg.vif.response_driver_cb.rintg  <= 'x;
       cfg.vif.response_driver_cb.error  <= 'x;
       rdata_queue.get(tr);
       if(cfg.vif.response_driver_cb.reset) continue;
-      cfg.vif.wait_clks(tr.rvalid_delay);
+
+      for (int i = 0;i < tr.rvalid_delay; ++i) begin
+        @(cfg.vif.response_driver_cb);
+      end
+
       if(~cfg.vif.response_driver_cb.reset) begin
         cfg.vif.response_driver_cb.rvalid <= 1'b1;
         cfg.vif.response_driver_cb.error  <= tr.error;