FAFT: Remove the backwards-compatible way to handle dev_key_path

The FAFT utils library is now deployable like others FAFT code.
Don't need to maintain the backwards compatibility.

BUG=None
TEST=Executed the RPC server.

Change-Id: I67aa3add5f8ad6473679eff20fdce8c550ee8ff5
Reviewed-on: https://chromium-review.googlesource.com/290582
Commit-Ready: Wai-Hong Tam <waihong@chromium.org>
Tested-by: Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Wai-Hong Tam <waihong@chromium.org>
1 file changed