[CodeGen][NewPM] Improve start/stop error message

Remove the pass-name-to-class-name lookup because it does not exist (that's why this error is thrown). Print the given name in the option instead.

llvm/include/llvm/Passes/CodeGenPassBuilder.h

@@ -609,14 +609,12 @@ Error CodeGenPassBuilder<Derived, TargetMachineT>::verifyStartStop(
     return Error::success();
 
   if (!Started)
-    return make_error<StringError>(
-        "Can't find start pass \"" +
-            PIC->getPassNameForClassName(Info.StartPass) + "\".",
-        std::make_error_code(std::errc::invalid_argument));
+    return make_error < StringError >
+               "Can't find start pass \"" + Info.StartPass + "\".",
+           std::make_error_code(std::errc::invalid_argument);
   if (!Stopped)
     return make_error<StringError>(
-        "Can't find stop pass \"" +
-            PIC->getPassNameForClassName(Info.StopPass) + "\".",
+        "Can't find stop pass \"" + Info.StopPass + "\".",
         std::make_error_code(std::errc::invalid_argument));
   return Error::success();
 }