net: dccp: ccids: lib: packet_history: use swap macro in tfrc_rx_hist_swap

Make use of the swap macro and remove unnecessary variable tmp.
This makes the code easier to read and maintain.

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ccids/lib/packet_history.c

@@ -149,10 +149,8 @@ static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b)
 {
 	const u8 idx_a = tfrc_rx_hist_index(h, a),
 		 idx_b = tfrc_rx_hist_index(h, b);
-	struct tfrc_rx_hist_entry *tmp = h->ring[idx_a];
 
-	h->ring[idx_a] = h->ring[idx_b];
-	h->ring[idx_b] = tmp;
+	swap(h->ring[idx_a], h->ring[idx_b]);
 }
 
 /*