Staging: batman-adv: fix whitespace style issues

This patch fixes unnecessary whitespaces before a quoted
newline that the remaining batman-adv files had.

Reported-by: Luis de Bethencourt <luisbg@ubuntu.com>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>