mediatek: add support for Acer Predator W6d and Acer Vero W6m

mediatek: add support for Acer Predator W6d and Acer Vero W6m

This commit adds support for two variants of the already supported router
Acer Predator Connect W6: The Acer Predator Connect W6d (W6 without 6 GHz
wifi) and the Acer Connect Vero W6m (W6 without 2.5G eth1 port, usb3 port,
and the 6 on-board gpio RGB LEDs, and with a KTD2026 RGB LED controller
instead of the KTD2061 LED controller of the W6/W6d).

The device tree for the W6m refers to the KTD202x driver suggested in
PR #16860.

Patching target/linux/mediatek/filogic/base-files/lib/upgrade/platform.sh
removes the code repetition in (old) lines 121 to 124 on the occasion.

This is the last of four commits into which the original commit was split
to make reviews easier and more targeted.

Signed-off-by: George Oldfort <openwrt@10099.de>
Link: https://github.com/openwrt/openwrt/pull/16861
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit 2898d1d1269a841e5bb8673801bd2a04ad120031)
Link: https://github.com/openwrt/openwrt/pull/17097
Signed-off-by: Petr Štetiar <ynezz@true.cz>