Revert "[lldb] Fix ppc64 detection in lldb"

This reverts commit f114f009.

Due to hitting an assert on our lldb bots:
https://lab.llvm.org/buildbot/#/builders/96/builds/22715

../llvm-project/lldb/source/Plugins/Process/elf-core/ThreadElfCore.cpp:170:
virtual lldb::RegisterContextSP ThreadElfCore::CreateRegisterContextForFrame(
lldb_private::StackFrame *): Assertion `false && "Architecture or OS not supported"' failed.