cfg80211: fix WoWLAN wakeup tracing

commit a92eecbb upstream.

If the device reports a non-wireless wakeup reason, the
tracing code crashes trying to dereference a NULL pointer.
Fix this by checking the pointer on all accesses and also
add a non_wireless tag to the event.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>