Staging: batman-adv: Fix the naming of the debug option.

So that the configuration hierarchy is correct, set the debug option
to have the same base as the main BATMAN option.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>