Use the correct batch size for vgg16 training (#583)
Summary:
The batch size for train was set to 256.
Source: https://arxiv.org/pdf/1409.1556.pdf
Pull Request resolved: https://github.com/pytorch/benchmark/pull/583
Reviewed By: aaronenyeshi
Differential Revision: D32841472
Pulled By: xuzhao9
fbshipit-source-id: b636a1fac01ce829b4b14834ee663f6ce7bd8d52
