device/fido: decomplexify AuthenticatorGetInfoResponse

It's just a struct, no need to wrap everything in trivial getters and
setters.

Change-Id: Ib350d3db0ed2bc48ed35c2cd4c49f52c2ec12c47
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1577677
Auto-Submit: Adam Langley <agl@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#653011}