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

Close #77201. When linking code with a R_X86_64_TPOFF64 relocation, LLD
exits with an 'unknown reloaction' error message due to two missing
cases in relocation switch statements. This patch adds in those cases so
that LLD successfully links code R_X86_64_TPOFF64 relocations.