DMA: Delay GPU transfers by block count

Needs real GPU timings, but fixes NFS5 in the meantime.

src/core/dma.cpp

@@ -197,6 +197,15 @@ TickCount DMA::GetTransferDelay(Channel channel) const
     }
     break;
 
+    case Channel::GPU:
+    {
+      if (cs.channel_control.sync_mode == SyncMode::Request)
+        return cs.block_control.request.GetBlockCount();
+      else
+        return 1;
+    }
+    break;
+
     default:
       return 1;
   }