[MC] Remove ELFObjectWriter::fixSymbolsInTLSFixups
Finish the migration started by
eea7d32bd262bb5f61790c42ebaa147aa26c3979.
STT_TLS setting has been moved to backend getRelocType.
75f5a4f0dc7d96134cca86543ef3f86ef218ce77 migrated the last target, VE.
