don't use Scala to Chisel implicit conversions outside of rocket

src/main/scala/rocket/dcache.scala

@@ -10,6 +10,7 @@ import uncore.coherence._
 import uncore.constants._
 import uncore.util._
 import util._
+import Chisel.ImplicitConversions._
 import cde.{Parameters, Field}
 
 class DCacheDataReq(implicit p: Parameters) extends L1HellaCacheBundle()(p) {