Fix ITIM deallocation during I$ refill causing data corruption

Deallocation can change repl_way, which violates the assumption that it
remains constant throughout refill.

The workaround described in commit 3db066303b
still suffices, provided only the hart that owns the ITIM changes the ITIM
allocation.

This subsumes commit 3db066303b.

src/main/scala/rocket/ICache.scala

@@ -294,7 +294,7 @@ class ICacheModule(outer: ICache) extends LazyModuleImp(outer)
             val enable = scratchpadWayValid(scratchpadWay(a.address))
             when (!lineInScratchpad(scratchpadLine(a.address))) {
               scratchpadMax.get := scratchpadLine(a.address)
-              when (enable) { invalidate := true }
+              invalidate := true
             }
             scratchpadOn := enable
           }