batman-adv: Drop NULL check before dropping references

The check if a batman-adv related object is NULL or not is now directly in
the batadv_*_put functions. It is not needed anymore to perform this check
outside these function:

The changes were generated using a coccinelle semantic patch:

  @@
  expression E;
  @@
  - if (likely(E != NULL))
  (
  batadv_backbone_gw_put
  |
  batadv_claim_put
  |
  batadv_dat_entry_put
  |
  batadv_gw_node_put
  |
  batadv_hardif_neigh_put
  |
  batadv_hardif_put
  |
  batadv_nc_node_put
  |
  batadv_nc_path_put
  |
  batadv_neigh_ifinfo_put
  |
  batadv_neigh_node_put
  |
  batadv_orig_ifinfo_put
  |
  batadv_orig_node_put
  |
  batadv_orig_node_vlan_put
  |
  batadv_softif_vlan_put
  |
  batadv_tp_vars_put
  |
  batadv_tt_global_entry_put
  |
  batadv_tt_local_entry_put
  |
  batadv_tt_orig_list_entry_put
  |
  batadv_tt_req_node_put
  |
  batadv_tvlv_container_put
  |
  batadv_tvlv_handler_put
  )(E);

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>