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-ack.c b/net/rxrpc/ar-ack.c
index adc555e..7cb7e45 100644
--- a/net/rxrpc/ar-ack.c
+++ b/net/rxrpc/ar-ack.c
@@ -886,10 +886,11 @@
 	struct rxrpc_header hdr;
 	struct msghdr msg;
 	struct kvec iov[5];
+	enum rxrpc_call_event genbit;
 	unsigned long bits;
 	__be32 data, pad;
 	size_t len;
-	int genbit, loop, nbit, ioc, ret, mtu;
+	int loop, nbit, ioc, ret, mtu;
 	u32 abort_code = RX_PROTOCOL_ERROR;
 	u8 *acks = NULL;