dell-laptop: add 3 machines that has touchpad LED

Add "Vostro 3555", "Inspiron N311z", and "Inspiron M5110" into quirks,
so that they could have touchpad LED function work.

Signed-off-by: AceLan Kao <acelan.kao@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>