Provide key preparsing for the request_key_auth key type so that we can make
preparsing mandatory.  This does nothing as this type can only be set up
internally to the kernel.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NSteve Dickson <steved@redhat.com>
Acked-by: NJeff Layton <jlayton@primarydata.com>