[NFC][TableGen] Remove dead code.

[pengfei]

LGTM.

llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp

for (unsigned EIdx : Leaf.value().TraversableEdges.set_bits()) {
 
       // We're looking at the right edge. This leaf wants a vreg def so we'll
       // put it in partition 1.
       addToPartition(true, Leaf.index());
       TraversedEdgesForLeaf.set(EIdx);
       WantsEdge = true;
     }
 
-    bool isNotReg = false;
-    if (!WantsEdge && isNotReg) {
-      // If this leaf doesn't have an edge and we _don't_ want a register,
-      // then add it to partition 0.
-      addToPartition(false, Leaf.index());
-    } else if (!WantsEdge) {
+    if (!WantsEdge) {
       // If this leaf doesn't have an edge and we don't know what we want,
       // then add it to partition 0 and 1.
       addToPartition(false, Leaf.index());
       addToPartition(true, Leaf.index());
     }
 
     TraversedEdges.push_back(TraversedEdgesForLeaf);
   }