wifi: mac80211: reset the LED state when ifup fails

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: reset the LED state when ifup fails

When the first interface comes up, the radio LED is turned on. This can
start the TPT trigger timer, which continues running.

But if bringing up the interface fails then the timer keeps running and
won't be stopped by anything, eventually it can be freed:

ODEBUG: free active (active state 0) object: ffff888127e12130 object type: timer_list hint: tpt_trig_timer+0x0/0x300 net/mac80211/led.c:145
WARNING: CPU: 0 PID: 5923 at lib/debugobjects.c:612 debug_print_object+0x1a2/0x2b0
debug_check_no_obj_freed+0x4b7/0x600 lib/debugobjects.c:1129
kfree+0x436/0x670 mm/slub.c:6818
ieee80211_led_exit+0x162/0x1c0 net/mac80211/led.c:210
ieee80211_unregister_hw+0x27e/0x3a0 net/mac80211/main.c:1706
rt2x00lib_remove_dev+0x55b/0x670

Undo the LED state in the error path.