Fixup: rename BatchedTensorKey to Batched (#38798)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38798

This makes it more in-line with the other keys in the file
(DispatchKey.h).

Test Plan: Imported from OSS

Differential Revision: D21691789

Pulled By: zou3519

fbshipit-source-id: 8d8b902360c0238f67bd0e58f9d969cec4b63320

aten/src/ATen/BatchedTensorImpl.cpp

@@ -7,7 +7,7 @@ namespace at {
 
 BatchedTensorImpl::BatchedTensorImpl(Tensor value, BatchDims bdims)
   : TensorImpl(
-      c10::DispatchKeySet(DispatchKey::BatchedTensorKey),
+      c10::DispatchKeySet(DispatchKey::Batched),
       value.dtype(),
       value.device()
     )

aten/src/ATen/BatchedTensorImpl.h

@@ -84,7 +84,7 @@ struct TORCH_API BatchedTensorImpl : public c10::TensorImpl {
 };
 
 inline bool isBatched(const Tensor& tensor) {
-  return tensor.unsafeGetTensorImpl()->key_set().has(DispatchKey::BatchedTensorKey);
+  return tensor.unsafeGetTensorImpl()->key_set().has(DispatchKey::Batched);
 }
 
 // It is unsafe to call this on a Tensor that is not backed by a

c10/core/DispatchKey.cpp

@@ -40,6 +40,8 @@ const char* toString(DispatchKey t) {
       return "Autograd";
     case DispatchKey::BackendSelect:
       return "BackendSelect";
+    case DispatchKey::Batched:
+      return "Batched";
     case DispatchKey::TESTING_ONLY_GenericMode:
       return "TESTING_ONLY_GenericMode";
     case DispatchKey::Autocast:

c10/core/DispatchKey.h

@@ -154,7 +154,7 @@ enum class DispatchKey : uint8_t {
 
   // This is the dispatch key for BatchedTensorImpl, which is used to implement
   // batching rules for vmap.
-  BatchedTensorKey,
+  Batched,
 
   // TESTING: This is intended to be a generic testing tensor type id.
   // Don't use it for anything real; its only acceptable use is within a single