cablev2: ignore unknown algorithms.

The Android FIDO API throws an exception for unknown public-key
algorithms, but authenticators are supposed to ignore them. Therefore
catch and ignore the exception.

BUG=1002262

Change-Id: I44d23d9896583ebfe983c0be47d8a3cb763ad271
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2174927
Commit-Queue: Adam Langley <agl@chromium.org>
Auto-Submit: Adam Langley <agl@chromium.org>
Reviewed-by: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#764747}