rxrpc: Calls should only have one terminal state

Condense the terminal states of a call state machine to a single state,
plus a separate completion type value.  The value is then set, along with
error and abort code values, only when the call is transitioned to the
completion state.

Helpers are provided to simplify this.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
index 5b45b6c..9c6685b 100644
--- a/net/rxrpc/conn_object.c
+++ b/net/rxrpc/conn_object.c
@@ -165,8 +165,8 @@
 		 * through the channel, whilst disposing of the actual call record.
 		 */
 		chan->last_service_id = call->service_id;
-		if (call->local_abort) {
-			chan->last_abort = call->local_abort;
+		if (call->abort_code) {
+			chan->last_abort = call->abort_code;
 			chan->last_type = RXRPC_PACKET_TYPE_ABORT;
 		} else {
 			chan->last_seq = call->rx_data_eaten;