ath6kl: convert to using %pOFn instead of device_node.name

In preparation to remove the node name pointer from struct device_node,
convert printf users to use the %pOFn format specifier.

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath6kl/init.c

@@ -710,8 +710,8 @@ static bool check_device_tree(struct ath6kl *ar)
 	for_each_compatible_node(node, NULL, "atheros,ath6kl") {
 		board_id = of_get_property(node, board_id_prop, NULL);
 		if (board_id == NULL) {
-			ath6kl_warn("No \"%s\" property on %s node.\n",
-				    board_id_prop, node->name);
+			ath6kl_warn("No \"%s\" property on %pOFn node.\n",
+				    board_id_prop, node);
 			continue;
 		}
 		snprintf(board_filename, sizeof(board_filename),