Respect io.coalescable for deq.valid in CoalShiftQueue

Otherwise disabling coalescer globally wouldn't work.

src/main/scala/tilelink/Coalescing.scala

@@ -235,7 +235,8 @@ class CoalShiftQueue[T <: Data](gen: T, entries: Int, config: CoalescerConfig) e
     // dequeue is valid when:
     // head entry is valid, has not been processed by downstream, and is not coalescable
     deq.bits := elts.map(_.head.bits)(i)
-    deq.valid := elts.map(_.head.valid)(i) && !deqDone(i) && !io.coalescable(i)
+    deq.valid := elts.map(_.head.valid)(i) && !deqDone(i) &&
+                 (!io.invalidate.valid || !io.coalescable(i))
 
     // can take new entries if not empty, or if full but shifting
     enq.ready := (!ctrl.full) || ctrl.shift