change linear benchmark shapes (#28228)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28228
as title
Test Plan:
```
buck run //caffe2/benchmarks/operator_benchmark/pt:linear_test
# ----------------------------------------
# PyTorch/Caffe2 Operator Micro-benchmarks
# ----------------------------------------
# Tag : short
# Benchmarking PyTorch: linear
# Mode: Eager
# Name: linear_N32_IN1024_OUT256
# Input: N: 32, IN: 1024, OUT: 256
Forward Execution Time (us) : 1501.918
# Benchmarking PyTorch: linear
# Mode: Eager
# Name: linear_N64_IN256_OUT100
# Input: N: 64, IN: 256, OUT: 100
Forward Execution Time (us) : 1175.672
Reviewed By: hl475
Differential Revision: D17980463
fbshipit-source-id: c8aaf6fa4d847037accb1e5b9ee04900690fd6ae
