speed up quantized interpolate for channels last (#66525)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66525
This should solve https://github.com/pytorch/pytorch/issues/60015
There were two `q_zero_point()` accesses inside a for loop which was
expensive. Moving them to before the loop sped things up 10x for a
microbenchmark.
Test Plan:
```
// comment out benchmarks unrelated to original issue, for simplicity
cd benchmarks/operator_benchmark
python -m pt.qinterpolate_test
// before: 2994 us
// after: 324 us
// full results: https://gist.github.com/vkuzo/cc5ef9526dc0cda170d6d63498c16453
```
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D31592422
fbshipit-source-id: b6078ac1039573bbe545275f7aedfd580910b459
