[lld] [lld][ELF][X86] Add missing X86_64_TPOFF64 case in switches (PR #77208)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> Thanks for the comments. I updated the x86-64-tls-pie.s test as you suggested and removed the new one I previously had added. I also updated the commit message as suggested.

Thanks. You can update the first comment, which will actually be used when a user with write permission clicks "Squash and merge"... The commit message is actually ignored.

https://github.com/llvm/llvm-project/pull/77208