Bluetooth: Use led_set_brightness() in LED trigger activate() callback

Bluetooth: Use led_set_brightness() in LED trigger activate() callback

A LED trigger's activate() callback gets called when the LED trigger
gets activated for a specific LED, so that the trigger code can ensure
the LED state matches the current state of the trigger condition
(LED_FULL when HCI_UP is set in this case).

led_trigger_event() is intended for trigger condition state changes and
iterates over _all_ LEDs which are controlled by this trigger changing
the brightness of each of them.

In the activate() case only the brightness of the LED which is being
activated needs to change and that LED is passed as an argument to
activate(), switch to led_set_brightness() to only change the brightness
of the LED being activated.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>