google/trogdor: add new variant kingoftown

This patch adds a new variant called kingoftown.
it's clamshell only, no FPR, eDP panel.

BUG=b:198365759
BRANCH=master
TEST=make

Signed-off-by: Kevin Chiu <kevin.chiu@quantatw.com>
Change-Id: I648664c50dfad11530a854f574f39264158b44e0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57433
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Bob Moragues <moragues@google.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

Documentation/security/vboot/list_vboot.md

@@ -170,6 +170,7 @@
 - Bubs
 - Coachz
 - Homestar
+- Kingoftown
 - Lazor
 - Marzipan
 - Mrbland