[llvm] Remove the assertion to unblock breakages (PR #88035)

[Lei Wang via llvm-commits]

wlei-llvm wrote:

> > OK, so this is because there is no profile loaded for this function in pre-link time (so it never run this profileIsValid), the attr is not set(unknown).
> 
> I'm curious why does this happen?

This can happen when meet:
1) there is no outline/top-level function in the profile( the function is all inlined into its caller or pre-inliner all inlines them). 
2) because we use flattened profile. In prelink, all the internal function's nested(children) profile doesn't have this function.
3) In post-link, one (external) function 's nested profile have this function. 

basically this is caused by the profile flattening. 

https://github.com/llvm/llvm-project/pull/88035