ramips: add new device ZyXEL Keenetic as kn

This device exactly same as NBG-419N but with USB port and USB Led.

Specification:

- SoC: Ralink RT3052 (MIPS24Kc) @384MHz
- RAM: 32 MiB
- Flash: 8 MiB
- WLAN: WiSoC 2T2R/300Mbps (2.4GHz)
- LAN: 4x100M
- WAN: 1x100M
- USB: 1x2.0

Installation via serial console (57600 8N1) from TFTP server
 - rename the firmware to something shorter, for example
   "sysupgrade.bin" (max. 32 chars)
 - copy firmware TFTP server's directory
 - when you power on device, and see U-Boot log, immediatly push "2"
   once.
 - You will see this message:
     2: System Load Linux Kernel then write to Flash via TFTP.
        Warning!! Erase Linux in Flash then burn new one. Are you sure?
 - Push "y", and enter: device IP, then TFTP server's IP, and then
   image firmware file name.

The firmware will be downloaded within ~30 seconds and flashed to the
device (It will take about 2 minutes).

Signed-off-by: Alexey Belyaev <spider@spider.vc>
[squash commits, compact commit message, fix compatible string, remove
superfluous pinmuxes]
Signed-off-by: Mathias Kresin <dev@kresin.me>

target/linux/ramips/base-files/etc/board.d/01_leds

@@ -222,6 +222,11 @@ ht-tm02)
 	ucidef_set_led_netdev "eth" "Ethernet" "$board:green:lan" "eth0"
 	set_wifi_led "$board:blue:wlan"
 	;;
+kn|\
+nbg-419n2)
+	set_usb_led "$board:green:usb"
+	set_wifi_led "rt2800pci-phy0::radio"
+	;;
 kn_rc|\
 kn_rf|\
 kng_rc)
@@ -265,10 +270,6 @@ mzk-ex750np)
 na930)
 	set_usb_led "$board:blue:status"
 	;;
-nbg-419n2)
-	set_usb_led "$board:green:usb"
-	set_wifi_led "rt2800pci-phy0::radio"
-	;;
 newifi-d1)
 	set_usb_led "$board:red:status"
 	;;

target/linux/ramips/base-files/etc/board.d/02_network

@@ -84,6 +84,7 @@ ramips_setup_interfaces()
 	hc5661a|\
 	hc5962|\
 	hlk-rm04|\
+	kn|\
 	kn_rc|\
 	mac1200rv2|\
 	miwifi-mini|\

target/linux/ramips/base-files/etc/diag.sh

@@ -24,6 +24,7 @@ get_status_led() {
 	e1700|\
 	ex3700|\
 	fonera20n|\
+	kn|\
 	kn_rc|\
 	kn_rf|\
 	kng_rc|\