Add targets:
* Ubiquiti UniFi 6 LR v2
* Ubiquiti UniFi 6 LR v2 (U-Boot mod)
This target does not have a RGB led bar like v1 did
Used target/linux/ramips/dts/mt7621_ubnt_unifi.dtsi as inspiration
The white dome LED is default-on, blue will turn on when the system is
in running state
Signed-off-by: Henrik Riomar <henrik.riomar@gmail.com>