Remove useless dynamic_cast<>().

Thanks Peter for pointing me to something that should have never been
committed to the llvm code base.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121648 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/RegionPass.cpp

@@ -259,8 +259,7 @@ void RegionPass::assignPassManager(PMStack &PMS,
 
     // [3] Assign manager to manage this new manager. This may create
     // and push new managers into PMS
-    Pass *P = dynamic_cast<Pass *>(RGPM);
-    TPM->schedulePass(P);
+    TPM->schedulePass(RGPM);
 
     // [4] Push new manager into PMS
     PMS.push(RGPM);