dfa4ede interface: fix return code of __interface_add()
a82a8f6 netifd: fix resource leak on error in netifd_add_dynamic()
fa2403d config: fix resource leaks on error in config_parse_interface()
85de9de interface: fix memory leak on error in __interface_add()
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>