This patch refactors the num_packets counter of a forw_packet in the
following three ways:

1) Removed dual-use of forw_packet::num_packets:
   -> now for aggregation purposes only
2) Using forw_packet::skb::cb::num_bcasts instead:
   -> for easier access in aggregation code later
3) make access to num_bcasts private to batadv_forw_packet_*()
Signed-off-by: NLinus Lüssing <linus.luessing@c0d3.blue>
[sven@narfation.org: Change num_bcasts to unsigned]
Signed-off-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>