leds: trigger: audio: Set module alias for module auto-loading

This a follow-up to 5edf7f11313d ("leds: trigger: Load trigger modules
on-demand if used as default trigger") and sets an alias for the audio
triggers.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/4663d2d8-660d-4af2-9f65-d95e95263923@gmail.com


Signed-off-by: Lee Jones <lee@kernel.org>