Rename FBGEMM quantized operators to generic quantized ops (#25678)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25678
As an effort to unify fbgemm and qnnpack at the dispatcher level, we need to have a generic name for the quantized backed ops.
Currently FBGEMM is guarded by the USE_FBGEMM macro and QNNPACK uses USE_QNNPACK.
ghstack-source-id: 89518961
Test Plan: buck test caffe2/test:quantized
Differential Revision: D17194364
fbshipit-source-id: 5960aedff6b8cb89eb3872c39b74caf54c0fbf20