If the device mode it toggled from 'ap' back to 'station' without actually
starting the access point ap_free attempts to zero out the psk, which
causes a crash because it had never been allocated (Start() never was
called). Since ap->psk is actually never used this was removed. Also added
a memset to zero out the pmk on cleanup.
This is the crash observed:
++++++++ backtrace ++++++++
0 0x7f6ffe978a80 in /lib64/libc.so.6
1 0x7f6ffe9d6766 in /lib64/libc.so.6
2 0x42dd51 in memset() at /usr/include/bits/string3.h:90
3 0x42ddd9 in ap_free() at src/ap.c:144
4 0x445ec6 in interface_instance_free() at ell/dbus-service.c:513
5 0x448650 in _dbus_object_tree_remove_interface() at ell/dbus-service.c:1595
6 0x40d980 in device_set_mode_sta() at src/device.c:2113
7 0x447d4c in properties_set() at ell/dbus-service.c:1861
8 0x448a33 in _dbus_object_tree_dispatch() at ell/dbus-service.c:1691
9 0x442587 in message_read_handler() at ell/dbus.c:285
10 0x43cac9 in io_callback() at ell/io.c:123
11 0x43bf5e in l_main_iterate() at ell/main.c:376
12 0x43c01c in l_main_run() at ell/main.c:419
13 0x40379d in main() at src/main.c:460
14 0x7f6ffe96288a in /lib64/libc.so.6
+++++++++++++++++++++++++++
a68e958f29