fix `dequantize_linear` (#21035)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21035
Fix the dtype error in `dequantize_linear`, it should accept the same dtype argument as `quantize_linear`
Differential Revision: D15521931
fbshipit-source-id: 0114c046a3f1046e42fca49c74c85e487fee8616
