batman-adv: set .owner to THIS_MODULE

[ Upstream commit 14a2e551faea53d45bc11629a9dac88f88950ca7 ]

If THIS_MODULE is not set, the module would be removed while debugfs is
being used.
It eventually makes kernel panic.

Fixes: c6c8fea2 ("net: Add batman-adv meshing protocol")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>