RxRPC: Allow key payloads to be passed in XDR form

Allow add_key() and KEYCTL_INSTANTIATE to accept key payloads in XDR form as
described by openafs-1.4.10/src/auth/afs_token.xg.  This provides a way of
passing kaserver, Kerberos 4, Kerberos 5 and GSSAPI keys from userspace, and
allows for future expansion.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rxrpc/ar-internal.h

@@ -401,22 +401,6 @@ struct rxrpc_call {
 	__be32			call_id;	/* call ID on connection  */
 };
 
-/*
- * RxRPC key for Kerberos (type-2 security)
- */
-struct rxkad_key {
-	u16	security_index;		/* RxRPC header security index */
-	u16	ticket_len;		/* length of ticket[] */
-	u32	expiry;			/* time at which expires */
-	u32	kvno;			/* key version number */
-	u8	session_key[8];		/* DES session key */
-	u8	ticket[0];		/* the encrypted ticket */
-};
-
-struct rxrpc_key_payload {
-	struct rxkad_key k;
-};
-
 /*
  * locally abort an RxRPC call
  */