[lld] [llvm] Revert "[LLVM] Use `reportFatalUsageError` for LTO usage errors" (PR #141000)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

Reverts should say why in the commit message so people don't have to go trawling through the prior PR to find out why

https://github.com/llvm/llvm-project/pull/141000