leds: trigger: Stop exporting trigger_list

leds: trigger: Stop exporting trigger_list

Commit 682e98564ffb ("leds: trigger: panic: Simplify
led_trigger_set_panic") removed the last external user of variable
trigger_list. So stop exporting it. If in future a need should arise
again to access this variable, I think we better add some accessor
instead of exporting the variable directly.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/ca185fb1-3a66-46b9-920e-bfecbe39c6bf@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>