batman-adv: Strip dots from variable macro kerneldoc

The commit 43756e34 ("scripts/kernel-doc: Add support for named
variable macro arguments") changed the handling of variable macro
parameters. The three dots of the argument must no longer be added to the
kernel doc. The support for the old format is scheduled to be removed in
the future.

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