mediatek: filogic: rename Cudy M3000 v1 to v1/v2

mediatek: filogic: rename Cudy M3000 v1 to v1/v2

The Cudy M3000 v1/v2 seem to have mostly identical hardware.
The M3000 v1 OpenWrt images work on the M3000 v2 (excluding
the v2 parts with a different PHY). Cudy also distributes one
firmware image that supports both routers.

Rename the human-readable device variant to "v1/v2" to match this.
Don't change the compatible property as that hooks into the
attended sysupgrade process.

The recent flash and PHY changes don't seem to be related to the v1/v2
split. There exist M3000 v2 with the Realtek PHY, see e.g.
https://github.com/openwrt/openwrt/pull/21584#issuecomment-3864992555

Signed-off-by: Jakub Vaněk <linuxtardis@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22259
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>