platform/x86: dell-laptop: Register ctl-led for speaker-mute

Some platforms have the speaker-mute led and
current driver doesn't control it.

If the platform support the control of speaker-mute led, register it

Signed-off-by: Koba Ko <koba.ko@canonical.com>
Link: https://lore.kernel.org/r/20230308062414.1048913-1-koba.ko@canonical.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>