batman-adv: only add recordroute information to icmp request/reply

Adding host information for record route is only required for ICMP
requests and replys, and should not be added to just any (future?)
packet type.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>