batman-adv: bla: use netif_rx_ni when not in interrupt context

batadv_bla_send_claim() gets called from worker thread context through
batadv_bla_periodic_work(), thus netif_rx_ni needs to be used in that
case. This fixes "NOHZ: local_softirq_pending 08" log messages seen
when batman-adv is enabled.

Fixes: 23721387

 ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@haltian.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>