Staging: batman-adv: Refactor routing.c

Break up a lot of the big functions up into many smaller ones. This
helps with readability and there is now a lot less code squashed
against the right hand margin.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NMarek Lindner <lindner_marek@yahoo.de>
Acked-by: NSimon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>