ieee802154: hwsim: Fix possible memory leak in hwsim_subscribe_all_others

In hwsim_subscribe_all_others, the error handling code performs
incorrectly if the second hwsim_alloc_edge fails. When this issue occurs,
it goes to sub_fail, without cleaning the edges allocated before.

Fixes: f25da51f

 ("ieee802154: hwsim: add replacement for fakelb")
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210611015812.1626999-1-mudongliangabcd@gmail.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>