Set instructionLanes back to 4

- An increase to 8 was mistakenly in the previous commit.

Change-Id: Ic7692b17d41e4c6881a3be1fa56567577ed30f1f

hdl/chisel/src/kelvin/Parameters.scala

diff --git a/hdl/chisel/src/kelvin/Parameters.scala b/hdl/chisel/src/kelvin/Parameters.scala
index 0080486..3546a74 100644
--- a/hdl/chisel/src/kelvin/Parameters.scala
+++ b/hdl/chisel/src/kelvin/Parameters.scala
@@ -52,7 +52,7 @@
   // Machine.
   val programCounterBits = 32
   val instructionBits = 32
-  val instructionLanes = 8
+  val instructionLanes = 4
 
   val vectorCountBits = log2Ceil(vectorBits / 8) + 1 + 2  // +2 stripmine