mediatek: filogic: add support for netis MEX605

mediatek: filogic: add support for netis MEX605

This commit adds support for the netis MEX605, which is a variant based on the netis NX30 V2.
1. Update brand naming from Netis to netis to follow the official branding.
2. Rename NX30V2 to NX30 V2 to correctly reflect it as the second version of the NX30.
3. Update variant notation for consistency.

cherry picked from commit c982357
1. Add 'model' to the DTS for netis NX30 V2 and define WiFi LED.
4. Fix typo.

Signed-off-by: Zhiwei Cao <bfdeh@126.com>
Signed-off-by: David Han <h96643864@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22726
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>