Input: leds - change config symbol dependency for audio mute trigger

In a follow-up patch implementation of the LED audio trigger will be
moved to sound/core/snd_ctl_led, including removal of config symbol
LEDS_AUDIO_TRIGGER. Also as of today the audio mute LED trigger
is effectively a no-op w/o config symbol SND_CTL_LED being defined.
Therefore switch the dependency to this config symbol.

Suggested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/6011ca63-187c-42dd-a5fd-7dd733d6257c@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>