remove cuda from add_test
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/27698
Test Plan:
```
buck run caffe2/benchmarks/operator_benchmark/pt:add_test -- --iterations 3
# ----------------------------------------
# PyTorch/Caffe2 Operator Micro-benchmarks
# ----------------------------------------
# Tag : short
# Benchmarking PyTorch: add
# Mode: Eager
# Name: add_M64_N64_K64_cpu
# Input: M: 64, N: 64, K: 64, device: cpu
Forward Execution Time (us) : 29691.940
# Benchmarking PyTorch: add
# Mode: Eager
# Name: add_M64_N64_K128_cpu
# Input: M: 64, N: 64, K: 128, device: cpu
Forward Execution Time (us) : 60820.813
Reviewed By: hl475
Differential Revision: D17855731
fbshipit-source-id: c64c530f4dbcb5b4132a88894b24e5658aa49d66
