dell-laptop: Fixed typo in touchpad LED quirk

Fixed the typo introduced from the below commit
5f1e88f4

 dell-laptop: Add 6 machines to touchpad led quirk

Reported-by: Carlos Alberto Lopez Perez <clopez@igalia.com>
Signed-off-by: AceLan Kao <acelan.kao@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>