Remove ProcessorSpecificPlugin. (#17789)
Summary:
It doesn't seem to be used.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17789
Reviewed By: ezyang
Differential Revision: D14382423
Pulled By: gchanan
fbshipit-source-id: 0ac3236c48979a1b2bcd615e307e55f10fd8eb77
