KEYS: user: Use key preparsing

Make use of key preparsing in user-defined and logon keys so that quota size
determination can take place prior to keyring locking when a key is being
added.

Also the idmapper key types need to change to match as they use the
user-defined key type routines.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>

diff --cc fs/nfs/idmap.c
Simple merge

diff --cc include/keys/user-type.h
Simple merge

diff --cc security/keys/user_defined.c
Simple merge