add workaround for some buggy controllers

[barbibulle]

Some controllers are buggy, so we need to try and workaround some quirks in order to use them.
Specifically here:

• some controllers return an error for some commands, even though they declare that they support them. Workaround: ignore the error, as if the command was not supported.

Also, for unknown HCI commands, some controllers return "command complete" events and some return "command status" events. So we need to support both case, regardless of whether the command is sync or async.