ns for fx: clean up linear in relationship mapping
Summary:
More cleanups in mappings:
1. makes the `nnqatd.Linear` entry be looked up dynamically
2. moves the `NonDynamicallyQuantizableLinear` down and marks it as edge case
Test plan:
```
python test/test_quantization.py -k FXGraphMatcher
python test/test_quantization.py -k FXNumericSuite
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76990
Approved by: https://github.com/jerryzh168
