batman-adv: tvlv: avoid race of cifsnotfound handler state

batman-adv: tvlv: avoid race of cifsnotfound handler state

TVLV handlers can have the flag BATADV_TVLV_HANDLER_OGM_CIFNOTFND set to
signal that the OGM handler should be called (with NULL for data) when the
specific TVLV container was not found in the OGM. This is used by:

* DAT
* GW
* Multicast (OGM + Tracker)

The state whether the handler was executed was stored in the struct
batadv_tvlv_handler. But the TVLV processing is started without any lock.
Multiple parallel contexts processing TVLVs would therefore overwrite each
others BATADV_TVLV_HANDLER_OGM_CALLED flag in the shared
batadv_tvlv_handler.

Drop the shared BATADV_TVLV_HANDLER_OGM_CALLED flag and instead determine,
per TVLV buffer, whether a matching container was present by scanning the
packet's buffer.

Cc: stable@kernel.org
Fixes: ef26157747d4 ("batman-adv: tvlv - basic infrastructure")
Signed-off-by: Sven Eckelmann <sven@narfation.org>