[CUDA]: Add frexp CUDA bfloat16 support (#133313)

Fixes #133263 Add CUDA bfloat16 support to cuda_frexp

Pull Request resolved: https://github.com/pytorch/pytorch/pull/133313
Approved by: https://github.com/ezyang, https://github.com/eqy

aten/src/ATen/native/cuda/UnaryOpsKernel.cu

@@ -262,7 +262,7 @@ void nan_to_num_kernel_cuda(
 }
 
 void frexp_kernel_cuda(TensorIteratorBase& iter) {
-  AT_DISPATCH_FLOATING_TYPES_AND(ScalarType::Half,
+  AT_DISPATCH_FLOATING_TYPES_AND2(kHalf, kBFloat16,
     // The iter.dtype() here is the dtype of mantissa output.
     // It's a floating point type and must be the same as the input's dtype.
     iter.dtype(),

torch/testing/_internal/common_methods_invocations.py

@@ -13661,8 +13661,6 @@ op_db: List[OpInfo] = [
                    op=torch.frexp,
                    ref=np.frexp,
                    dtypes=floating_types_and(torch.half, torch.bfloat16),
-                   dtypesIfCUDA=floating_types_and(torch.half),
-                   # skip testing torch.frexp as it is not supported by ROCm platform yet
                    decorators=[],
                    supports_forward_ad=True,
                    supports_fwgrad_bwgrad=True,