Refactor package hierarchy and remove legacy bus protocol implementations (#845)

* Refactors package hierarchy.

Additionally:
  - Removes legacy ground tests and configs
  - Removes legacy bus protocol implementations
  - Removes NTiles
  - Adds devices package
  - Adds more functions to util package

src/main/scala/groundtest/Status.scala

@@ -0,0 +1,23 @@
+// See LICENSE.SiFive for license details.
+
+package freechips.rocketchip.groundtest
+
+import Chisel._
+import freechips.rocketchip.util.ValidMux
+
+class GroundTestStatus extends Bundle {
+  val finished = Bool(OUTPUT)
+  val timeout = Valid(UInt(width = 4))
+  val error = Valid(UInt(width = 4))
+}
+
+object DebugCombiner {
+  def apply(debugs: Seq[GroundTestStatus]): GroundTestStatus = {
+    val out = Wire(new GroundTestStatus)
+    out.finished := debugs.map(_.finished).reduce(_ && _)
+    out.timeout  := ValidMux(debugs.map(_.timeout))
+    out.error    := ValidMux(debugs.map(_.error))
+    out
+  }
+}
+