Fix vectorized trigonometric functions for VSX (#86453)
Replace the remaining hand-written code in vec256_float_vsx.h by calls to Sleef functions similar to what was done in #59382 & #82646 after #41541
This fixes wrong results for e.g. `sin(1e20)`.
Fixes #85978
To fix #85978 I only needed to do the sin/cos functions to make the test pass but to not encounter the same issue again and again (see the previous PRs and issues) I checked the whole file for similar functions where a Sleef function could be used and changed those too. In the diff I've noticed the faulty whitespace so to make this complete I fixed that too, so it should now be done.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86453
Approved by: https://github.com/malfet
