[inductor][eazy] fix a typo in test (#120832)
In theory we can test anything, but the test name mentioned attention so we should multiple the inv_scale rather than divide it. And I guess that the initial intension of the test.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120832
Approved by: https://github.com/desertfire, https://github.com/jansel
