mac80211: implement non-peer station RSSI advertisement

For external purposes it might be interesting to
report the RSSI (last and average value) of all
the stations that an AP can hear on the channel.

This information can be used by external processes
meant to perform load balancing between different
APs in the same ESS

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
mac80211: add sta_rssi table in debugfs

User-space processes may be interested in reading
the table containing all the stations heard by an
AP for high-level purposes.

This patch adds a table in DebugFS containing all
the entries stored in sta_rssi_hash.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
mac80211: add AP RSSI advertisement runtime switch

This patch adds a switch to allow the user to turn the mechanism on or
off at runtime

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
batman-adv: add a batadv_priv module-wide list

This patch adds a module-wide (global variable) list which stores
each and every active batadv_priv object that batman-adv can create
along its life. A batadv_priv object is created each time a new mesh
network is initiated on the node, therefore such list would allow
developers to have a view of the current global state of all the
batman-adv networks the node belongs to.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
batman-adv: implement TT client checking function

This patch adds a new function aimed to check whether a MAC address is
registered as (local or global) TT client in _any_ of the batman-adv
networks which the host belongs to.

This function can be used by external modules to interact with
batman-adv and possibly change their behaviour. To achieve so, the
function has been declared in a new external, kernel-wide, header file
placed at include/net/batman-adv.h in the kernel tree.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
mac80211: filter stations based on any running batman-adv mesh network

Signed-off-by: Antonio Quartulli <ordex@autistici.org>