diplomacy: convert all helper objects to return nodes

src/main/scala/tilelink/CacheCork.scala

@@ -3,7 +3,6 @@
 package freechips.rocketchip.tilelink
 
 import Chisel._
-import chisel3.internal.sourceinfo.SourceInfo
 import freechips.rocketchip.config.Parameters
 import freechips.rocketchip.diplomacy._
 import scala.math.{min,max}
@@ -122,10 +121,5 @@ class TLCacheCork(unsafe: Boolean = false)(implicit p: Parameters) extends LazyM
 
 object TLCacheCork
 {
-  // applied to the TL source node; y.node := TLCacheCork()(x.node)
-  def apply(unsafe: Boolean = false)(x: TLOutwardNode)(implicit p: Parameters, sourceInfo: SourceInfo): TLOutwardNode = {
-    val cork = LazyModule(new TLCacheCork(unsafe))
-    cork.node :=? x
-    cork.node
-  }
+  def apply(unsafe: Boolean = false)(implicit p: Parameters): TLNode = LazyModule(new TLCacheCork(unsafe)).node
 }