Move a bunch more things into util package

A lot of utility code was just being imported willy-nilly from one
package to another. This moves the common code into util to make things
more sensible. The code moved were

 * The AsyncQueue and AsyncDecoupledCrossing from junctions.
 * All of the code in rocket's util.scala
 * The BlackBox asynchronous reset registers from uncore.tilelink2
 * The implicit definitions from uncore.util

src/main/scala/rocketchip/Configs.scala

@@ -5,12 +5,12 @@ package rocketchip
 import Chisel._
 import junctions._
 import rocket._
-import rocket.Util._
 import uncore.agents._
 import uncore.tilelink._
 import uncore.tilelink2.{LazyModule}
 import uncore.devices._
 import uncore.converters._
+import util._
 import coreplex._
 import scala.math.max
 import scala.collection.mutable.{LinkedHashSet, ListBuffer}