Revert: "Staging: batman-adv: Adding netfilter-bridge hooks"

This reverts commit 96d592ed.

The netfilter hook seems to be misused and may leak skbs in situations
when NF_HOOK returns NF_STOLEN. It may not filter everything as
expected. Also the ethernet bridge tables are not yet capable to
understand batman-adv packet correctly.

It was only added for testing purposes and can be removed again.

Reported-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>