ipq806x: Add support for Netgear Nighthawk Pro Gaming XR450

Motivation:
 Firmware with platform ID "XR450" required for easy installation.

Manufacturer pages:
 Product page: https://www.netgear.com/support/product/xr450
 Product Data Sheet: https://www.netgear.com/images/datasheet/networking/wifirouter/XR450.pdf
 Current firmware: https://www.downloads.netgear.com/files/GDC/XR450/XR450-V2.3.2.134.zip

Specifications:
Almost identical to Netgear XR500(https://openwrt.org/toh/hwdata/netgear/netgear_xr500)

Differences:
	Platform ID: XR450, utilized for firmware validation
	WLAN 2.4GHz: b/g/n Supports QAM64 (XR500 QAM256)

SoC: Qualcomm Atheros IPQ8065
RAM: 512 MB
Storage: 256 MiB
Wireless: Qualcomm Atheros QCA9984
Switch: Qualcomm Atheros AR8337 rev. 2
Ethernet: 5x 1000/100/10
USB: 2x 3.0

Install via WEB GUI (recommended):
1. Navigate within GUI to firmware update section
2. Select openwrt-ipq806x-netgear_xr450-squashfs-factory.img
3. Dismiss downgrade warning

Install via TFTP recovery (same as XR500/R7800):

1. Configure host PC to use static address 192.168.1.10 https://openwrt.org/toh/netgear/r7800#prerequisites_for_tftp_flashing
2. Flash openwrt-ipq806x-netgear_xr450-squashfs-factory.img using procedure https://openwrt.org/toh/netgear/r7800#tftp_flashing_process

Revert to stock firmware
1. Download current manufacturer firmware, decompress zip file to obtain img file
2. Use TFTP recovery method flash img file (currently XR450-V2.3.2.134.img)
ipq806x: add support to netgear_xr450

Signed-off-by: Andrzej Mialkowski <andrzej.mialkowski@gmail.com>

target/linux/ipq806x/base-files/etc/board.d/01_leds

@@ -37,6 +37,7 @@ netgear,d7800 |\
 netgear,r7500 |\
 netgear,r7500v2 |\
 netgear,r7800 |\
+netgear,xr450 |\
 netgear,xr500)
 	ucidef_set_led_usbport "usb1" "USB 1" "white:usb1" "usb1-port1" "usb2-port1"
 	ucidef_set_led_usbport "usb2" "USB 2" "white:usb2" "usb3-port1" "usb4-port1"

target/linux/ipq806x/base-files/etc/board.d/02_network

@@ -59,6 +59,7 @@ nec,wg2600hp3)
 		"2:lan" "3:lan" "4:lan" "5:lan" "0@eth1" "1:wan" "6@eth0"
 	;;
 netgear,r7800 |\
+netgear,xr450 |\
 netgear,xr500 |\
 tplink,c2600 |\
 tplink,vr2600v)

target/linux/ipq806x/base-files/lib/upgrade/platform.sh

@@ -17,6 +17,7 @@ platform_do_upgrade() {
 	netgear,r7500 |\
 	netgear,r7500v2 |\
 	netgear,r7800 |\
+	netgear,xr450 |\
 	netgear,xr500 |\
 	nokia,ac400i |\
 	qcom,ipq8064-ap148 |\