batman-adv: Prepare framework for hardif genl config

The batman-adv configuration interface was implemented solely using sysfs.
This approach was condemned by non-batadv developers as "huge mistake".
Instead a netlink/genl based implementation was suggested.

Beside the mesh/soft-interface specific configuration, the
slave/hard-interface have B.A.T.M.A.N. V specific configuration settings.
The genl interface reflects this by allowing to get/set it using the
hard-interface specific commands.

The BATADV_CMD_GET_HARDIFS (or short version BATADV_CMD_GET_HARDIF) is
reused as get command because it already allow sto dump the content of
other information from the slave/hard-interface which are not yet
configuration specific.

The set command BATADV_CMD_SET_HARDIF will also notify interested userspace
listeners of the "config" mcast group using the BATADV_CMD_SET_HARDIF
command message type that settings might have been changed and what the
current values are.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

include/uapi/linux/batman_adv.h

@@ -398,9 +398,15 @@ enum batadv_nl_commands {
 	BATADV_CMD_GET_ROUTING_ALGOS,
 
 	/**
-	 * @BATADV_CMD_GET_HARDIFS: Query list of hard interfaces
+	 * @BATADV_CMD_GET_HARDIF: Get attributes from a hardif of the
+	 *  current softif
 	 */
-	BATADV_CMD_GET_HARDIFS,
+	BATADV_CMD_GET_HARDIF,
+
+	/**
+	 * @BATADV_CMD_GET_HARDIFS: Alias for @BATADV_CMD_GET_HARDIF
+	 */
+	BATADV_CMD_GET_HARDIFS = BATADV_CMD_GET_HARDIF,
 
 	/**
 	 * @BATADV_CMD_GET_TRANSTABLE_LOCAL: Query list of local translations
@@ -453,6 +459,12 @@ enum batadv_nl_commands {
 	 */
 	BATADV_CMD_SET_MESH,
 
+	/**
+	 * @BATADV_CMD_SET_HARDIF: Set attributes for hardif of the
+	 *  current softif
+	 */
+	BATADV_CMD_SET_HARDIF,
+
 	/* add new commands above here */
 
 	/**