batman-adv: rename batadv_softif_destroy to reflect sysfs use case

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
CC: Sven Eckelmann <sven@narfation.org>
Acked-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
3 files changed