append caffe2 prefix to dnnlowp cmd line options (#15582)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15582
Following convention of having caffe2_ prefix in command line options
Reviewed By: viswanathgs
Differential Revision: D13252055
fbshipit-source-id: 142a6395b832f211f34d0a87ec2d62c1e5fcdc69
