[llvm] [PowerPC] Mark llvm.tan on vectors as expand (PR #95507)

[Farzon Lotfi via llvm-commits]

farzonl wrote:

> Hi @farzonl, do you mean this patch is not needed, because you will fix vector version of these math library nodes together?

My plan was to do an expand in `TargetLoweringBase.cpp` in this pr: https://github.com/llvm/llvm-project/pull/95517 That way I knock out more platforms at once.

I'm doing spot testing to  make sure f16 and vector work. Also PowerPC needs llvm vectors to convert to IBM MASS  Vector functions and  my change doesn't do that either.

https://github.com/llvm/llvm-project/pull/95507