dtlb now arbitrates between cpu, vec, and vec pf

rocket/src/main/scala/consts.scala

@@ -238,4 +238,8 @@ object Constants
   val VIMM_VLEN = UFix(0, 1)
   val VIMM_ALU = UFix(1, 1)
   val VIMM_X = UFix(0, 1)
+
+  val DTLB_VEC = 0
+  val DTLB_VPF = 1
+  val DTLB_CPU = 2
 }