Staging: batman-adv: move queue counters into bat_priv

to support multiple mesh devices later, we need to move global variables
like the queues into corresponding private structs bat_priv of the soft
devices.

Note that this patch still has a lot of FIXMEs and depends on the global
soft_device variable. This should be resolved later, e.g. by referencing
the parent soft device in batman_if.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
[sven.eckelmann@gmx.de: Rework on top of current version]
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>