[TI removal] Remove a unnecessary use of `TerminatorInst` from an IR

header. NFC.

Part of the removal of `TerminatorInst` from the type hierarchy.

llvm-svn: 344495

llvm/include/llvm/IR/CFG.h

@@ -73,7 +73,7 @@ public:
 
   inline reference operator*() const {
     assert(!It.atEnd() && "pred_iterator out of range!");
-    return cast<TerminatorInst>(*It)->getParent();
+    return cast<Instruction>(*It)->getParent();
   }
   inline pointer *operator->() const { return &operator*(); }