qualcommax: ipq807x: add support for Linksys HomeWRK

Hardware specification:
========
SoC: Qualcomm IPQ8174
Flash: 1GB (Micron MT29F8G08ABBCAH4 or AMD/Spansion S34MS08G2)
RAM: 2GB (2x Kingston B5116ECMDXGJD or ESMT M15T2G16128A DDR3L)
Ethernet: 4x 10/100/1000Mbps (Qualcomm QCA8075)
WiFi1: 5GHz ax 2x2 (Qualcomm QCN5054 + Skyworks SKY85755-11) - channels 36-64 (low band)
WiFi2: 2.4GHz ax 2x2 (Qualcomm QCN5024 + Skyworks SKY85340-11)
WiFi3: 5GHz ax 4x4 (Qualcomm QCN5054 + Skyworks SKY85755-11) - channels 100-177 (high band)
LED: 1x RGB status (NXP PCA9633)
USB: 1x USB 3.0
Button: WPS, Reset

Flash instructions:
========
1. Installation from initramfs image using USB drive:
Put the initramfs image on the USB drive:
- dd bs=1M if=openwrt-qualcommax-ipq807x-linksys_homewrk-initramfs-uImage.itb of=/dev/sdX
Connect serial console (JST PH 6-pin connector):
- 1 - GND, 2 - TX, 4 - RX (115200, 8N1, 3.3V)
Stop u-boot and run:
- usb start && usbboot 44000000 0 && bootm 44000000
Write firmware to the flash from initramfs:
- sysupgrade -n openwrt-qualcommax-ipq807x-linksys_homewrk-squashfs-sysupgrade.bin
or
- ubiformat /dev/mtd22 -y -f openwrt-qualcommax-ipq807x-linksys_homewrk-squashfs-factory.ubi

2. USB recovery:
Put the initramfs image on the USB:
- dd bs=1M if=openwrt-qualcommax-ipq807x-linksys_homewrk-initramfs-uImage.itb of=/dev/sdX
Set u-boot env:
- fw_setenv bootusb 'usb start && usbboot 44000000 0 && bootm 44000000'
- fw_setenv bootcmd 'run bootusb; bootipq'

Signed-off-by: Paweł Owoc <frut3k7@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/17463
Signed-off-by: Robert Marko <robimarko@gmail.com>

package/boot/uboot-envtools/files/qualcommax_ipq807x

@@ -29,6 +29,11 @@ edimax,cax1800)
 	[ -n "$idx" ] && \
 		ubootenv_add_uci_config "/dev/mtd$idx" "0x0" "0x10000" "0x20000"
 	;;
+linksys,homewrk)
+	idx="$(find_mtd_index 0:appsblenv)"
+	[ -n "$idx" ] && \
+		ubootenv_add_uci_config "/dev/mtd$idx" "0x0" "0x40000" "0x40000"
+	;;
 linksys,mx4200v1|\
 linksys,mx4200v2|\
 linksys,mx5300|\