ramips: add missing LEDs and modem control for ASUS 4G-AX56

ramips: add missing LEDs and modem control for ASUS 4G-AX56

Add missing LEDs and modem control for ASUS 4G-AX56
 - wifi2.4G white
 - wifi5G   white
 - wan      two-coloured, white and red
 - modem    four-coloured white, blue, yellow and red
   change
      label = "xxxx:modem";
   to
      color = <LED_COLOR_ID_xxxx>;
      function = LED_FUNCTION_MOBILE;
 - rssi-1   white
 - rssi-2   white
 - rssi-3   white

and modem reboot and reset

Combined into one commit

Signed-off-by: Henrik Ginstmark <henrik@ginstmark.se>
Link: https://github.com/openwrt/openwrt/pull/17927
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>