ipq40xx: Add support Netgear LBR20

ipq40xx: Add support Netgear LBR20

**Netgear LBR20** is a router with two gigabit ethernets , three wifi radios and integrated LTE cat.18 modem.

SoC Type: Qualcomm IPQ4019
RAM: 512 MiB
Flash: 256 MiB , SLC NAND, 2 Gbit (Macronix MX30LF2G18AC)
Bootloader: U-Boot
Modem: LTE CAT.18 Quectel EG-18EA ,  Max. 1.2Gbps downlink / 150Mbps uplink

WiFi class AC2200:
- radio0 : 5G on QCA9888 , WiFi5- 802.11a/n/ac MU-MIMO 2x2 , 887Mbps , 80MHz - limited for low channels
- radio1: 2,4G on IPQ4019 ,WiFi4- 802.11b/g/n MIMO2x2 300Mbps 40Mhz
- radio2: 5G on IPQ4019 , WiFi5- 802.11a/n/ac MU-MIMO 2x2 , 887Mbps ,80Mhz - limited for high channels  (from 100 up to 165) . Becouse of DFS remember to set country before turning on.

Ethernet: 2x1GbE (WAN/LAN1, LAN2)
LEDs:  section power : green and red  , section on top (orbi) drived by TLC59208F: red, green ,blue and white
USB ports: No
Buttons:  2 Reset and SYNC(WPS)
Power: 12 VDC, 2,5 A
Connector type: Barrel

OpenWRT Installation
1. Simplest way is just do upgrade from webpage with *factory.img
2. You can also do it with standard tool for Netgear's debricking - NMPRFlash
3. Most advanced way is to open device , connect to UART console and :
- Prepare OpenWrt initramfs image in TFTP server root (server IP 192.168.1.10)
- Connect serial console (115200,8n1) to UART connector
- Connect TFTP server to RJ-45 port
- Stop in u-Boot and run u-Boot command:

> setenv serverip 192.168.1.10
> set fdt_high 0x85000000
> tftpboot 0x83000000 openwrt-ipq40xx-generic-netgear_lbr20-initramfs-zImage.itb
> bootm 0x83000000

- Login via ssh
- upload or download *sysupgrade.bin ( like wget ... or scp transfer)
-  Install image via "sysupgrade -n" (like “sysupgrade -n /tmp/openwrt-ipq40xx-generic-netgear_lbr20-squashfs-sysupgrade.bin”)

Back to Stock
- Download firmware from official Netgear's webpage , it will be *.img file after decompressing.
- Use NMRPFlash tool  ( detailed insructions on project page https://github.com/jclehner/nmrpflash )

Open the case
- Unscrew nuts and remove washers from antenna's conectors.
- There are two Torx T10 screws under the label next to antenna conectors. You have to unglue this label from left and right corner to get it
- Two parts of shell covers will slide out from eachother , you have to unglue two small rubber pads and namplate sticker on bottom to do that.
- PCB is screwed with 4Pcs of Torx T10 screws
- Before lifting up PCB remove pigtiles for LTE antennas and release them from PCB and radiator (black and white wires)
- On other side of PCB ,in left bottom corner there is already soldered with 4 pins UART connector for console. Counting from left it is  +3,3V , TX , RX ,GND (reffer to this picture: https://i.ibb.co/Pmrf9KB/20240116-103524.jpg )

BDF's files are in firmware_qca-wireless  https://github.com/openwrt/firmware_qca-wireless/ and in parallel sent to ath10k@lists.infradead.org.

Signed-off-by: Marcin Gajda <mgajda@o2.pl>