batman-adv: Remove dev_queue_xmit return code exception

No caller of batadv_send_skb_to_orig is expecting the results to be -1
(-EPERM) anymore when the skbuff was not consumed. They will instead expect
that the skbuff is always consumed. Having such return code filter is
therefore not needed anymore.

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