axi4: add a minLatency parameter

src/main/scala/uncore/tilelink2/RegisterRouter.scala

@@ -18,7 +18,7 @@ class TLRegisterNode(address: AddressSet, concurrency: Int = 0, beatBytes: Int =
       supportsPutFull    = TransferSizes(1, beatBytes),
       fifoId             = Some(0))), // requests are handled in order
     beatBytes  = beatBytes,
-    minLatency = min(concurrency, 1))) // the Queue adds at least one cycle
+    minLatency = min(concurrency, 1))) // the Queue adds at most one cycle
 {
   require (address.contiguous)