rtw88: Fix an error message

The WARN_ON() macro takes a condition, not a warning message.  I've
changed this to use WARN() instead.

Fixes: 4136214f ("rtw88: add BT co-existence support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtw88/coex.c

@@ -1059,7 +1059,7 @@ static void rtw_coex_set_ant_path(struct rtw_dev *rtwdev, bool force, u8 phase)
 		pos_type = COEX_SWITCH_TO_WLG_BT;
 		break;
 	default:
-		WARN_ON("unknown phase when setting antenna path\n");
+		WARN(1, "unknown phase when setting antenna path\n");
 		return;
 	}