rxrpc: Convert call flag and event numbers into enums

Convert call flag and event numbers into enums and move their definitions
outside of the struct.

Also move the call state enum outside of the struct and add an extra
element to count the number of states.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/ar-call.c b/net/rxrpc/ar-call.c
index a9e05db..d9a8eeb 100644
--- a/net/rxrpc/ar-call.c
+++ b/net/rxrpc/ar-call.c
@@ -28,7 +28,7 @@
  */
 unsigned rxrpc_dead_call_expiry = 2 * HZ;
 
-const char *const rxrpc_call_states[] = {
+const char *const rxrpc_call_states[NR__RXRPC_CALL_STATES] = {
 	[RXRPC_CALL_CLIENT_SEND_REQUEST]	= "ClSndReq",
 	[RXRPC_CALL_CLIENT_AWAIT_REPLY]		= "ClAwtRpl",
 	[RXRPC_CALL_CLIENT_RECV_REPLY]		= "ClRcvRpl",