net: ieee802154: Provide a kdoc to the address structure

Give this structure a header to better explain its content.
Signed-off-by: David Girault <david.girault@qorvo.com>
[miquel.raynal@bootlin.com: Isolate this change from a bigger commit and
                            reword the comment]
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20220201180956.93581-1-miquel.raynal@bootlin.comSigned-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

include/net/cfg802154.h

@@ -227,6 +227,16 @@ static inline void wpan_phy_net_set(struct wpan_phy *wpan_phy, struct net *net)
 	write_pnet(&wpan_phy->_net, net);
 }
 
+/**
+ * struct ieee802154_addr - IEEE802.15.4 device address
+ * @mode: Address mode from frame header. Can be one of:
+ *        - @IEEE802154_ADDR_NONE
+ *        - @IEEE802154_ADDR_SHORT
+ *        - @IEEE802154_ADDR_LONG
+ * @pan_id: The PAN ID this address belongs to
+ * @short_addr: address if @mode is @IEEE802154_ADDR_SHORT
+ * @extended_addr: address if @mode is @IEEE802154_ADDR_LONG
+ */
 struct ieee802154_addr {
 	u8 mode;
 	__le16 pan_id;