qualcommax: ipq60xx: add Linksys MR7350 support

qualcommax: ipq60xx: add Linksys MR7350 support

Linksys MR7350 is a 802.11ax Dual-band router/AP.
Specifications:
* CPU: Qualcomm IPQ6000 Quad core Cortex-A53(A73) 1.5GHz
* RAM: 512MB of DDR3
* Storage: 256Mb NAND
* Ethernet: 5x1G RJ45 ports (QCA8075)
* WLAN:
	* 2.4GHz: Qualcomm QCN5022 2x2 802.11b/g/n/ax 574 Mbps PHY rate
	* 5GHz: Qualcomm QCN5052 2x2@80MHz or  802.11a/b/g/n/ac/ax 1201 Mbps PHY rate
* LED-s:
	* RGB system led
	* USB blue led

* Buttons: 1x Soft reset 1x WPS
* Power: 12V DC Jack

Installation instructions:
Open Linksys Web UI - http://192.168.1.1/ca or http://10.65.1.1/ca depending on your setup.
Login with your admin password. The default password can be found on a sticker under the device.
To enter into the support mode, click on the “CA” link and the bottom of the page.
Open the “Connectivity” menu and upload the squash-factory image with the “Choose file” button.
Click start. Ignore all the prompts and warnings by click “yes” in all the popups.
The Wifi radios are turned off by default. To configure the router, you will need to connect your computer to the LAN port of the device.
Then you would need to write openwrt to the other partition for it to work
- First Check booted partition:
fw_printenv -n boot_part

- Change the partition:
fw_setenv boot_part 1
or
fw_setenv boot_part 2
depending on the current partition

- Then install Openwrt to the other partition if booted in slot 1:
mtd -r -e alt_kernel -n write openwrt-qualcommax-ipq60xx-linksys_mr7350-squashfs-factory.bin alt_kernel

- If in slot 2:
mtd -r -e kernel -n write openwrt-qualcommax-ipq60xx-linksys_mr7350-squashfs-factory.bin kernel

Co-Authored-by: Chukun Pan <amadeus@jmu.edu.cn>
Co-Authored-by: Robert Marko <robimarko@gmail.com>
Signed-off-by: Vladyslav Andreichykov <vladdrako007@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/14807
Signed-off-by: Robert Marko <robimarko@gmail.com>