wifi: ath9k: Use swap() to improve ath9k_hw_get_nf_hist_mid()

Use the swap() macro to simplify the ath9k_hw_get_nf_hist_mid() function
and improve its readability.

Fixes the following Coccinelle/coccicheck warning reported by
swap.cocci:

  WARNING opportunity for swap()

Compile-tested only.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20240710185743.709742-2-thorsten.blum@toblux.com

drivers/net/wireless/ath/ath9k/calib.c

@@ -32,11 +32,8 @@ static int16_t ath9k_hw_get_nf_hist_mid(int16_t *nfCalBuffer)
 
 	for (i = 0; i < ATH9K_NF_CAL_HIST_MAX - 1; i++) {
 		for (j = 1; j < ATH9K_NF_CAL_HIST_MAX - i; j++) {
-			if (sort[j] > sort[j - 1]) {
-				nfval = sort[j];
-				sort[j] = sort[j - 1];
-				sort[j - 1] = nfval;
-			}
+			if (sort[j] > sort[j - 1])
+				swap(sort[j], sort[j - 1]);
 		}
 	}
 	nfval = sort[(ATH9K_NF_CAL_HIST_MAX - 1) >> 1];