Make a directory for the config package (#464)

* [config] make dir structure mirror packages

* [config] expunge max_int

src/main/scala/groundtest/Configs.scala

@@ -16,7 +16,6 @@ import config._
 import scala.math.max
 import coreplex._
 import rocketchip._
-import util.ConfigUtils._
 
 /** Actual testing target Configs */