Set cmdqDepth in VConvControl to instructionLanes

- This lets the testbench pass on instructionLanes configurations other
  than 4.

Change-Id: Ic5647aaa0c1cb38694ebaae8bfbea5365af515dc

hdl/chisel/src/kelvin/vector/VConvCtrl.scala

diff --git a/hdl/chisel/src/kelvin/vector/VConvCtrl.scala b/hdl/chisel/src/kelvin/vector/VConvCtrl.scala
index ebea853..5069088 100644
--- a/hdl/chisel/src/kelvin/vector/VConvCtrl.scala
+++ b/hdl/chisel/src/kelvin/vector/VConvCtrl.scala
@@ -39,7 +39,7 @@
   })
 
   // A usable depth of outstanding commands.
-  val cmdqDepth = 4
+  val cmdqDepth = p.instructionLanes
 
   val e = new VEncodeOp()