[llvm] [AsmPrint] Correctly factor function entry count when dumping MBB frequencies (PR #67826)

[Matthias Braun via llvm-commits]

MatzeB wrote:

I don't think I have a strong opinion on `float` vs `double` (though FWIW I also don't see a real indication that `double` would be strictly necessary). If performance is a concern then we really should cache the `1.0 / getEntryFreq()` result in `MachineBLockFrequencyInfo`, but I also have no indication that perf is relevant here so I guess I'm good with switching the API to double.

https://github.com/llvm/llvm-project/pull/67826