mvebu: add support for GL.iNet GL-MV1000

mvebu: add support for GL.iNet GL-MV1000

This patch adds supports for GL-MV1000.

Specification:
	- SOC: Marvell Armada 88F3720 (1GHz)
	- Flash: 16MB (W25Q128FWSIG)
	- RAM: 1GB DDR4
	- Ethernet: 3x GE (1 WAN + 2 LAN)
	- EMMC: 8GB EMMC (KLM8G1GETF-B041)
	- MicroSD: 1x microSD slot
	- USB: 1x USB 2.0 port(TypeA),1x USB 3.0 port(TypeC)
	- Button: 1x reset button,1x slide switch
	- LED: 3x greed LED
	- UART: 1x UART on PCB (JP1: 3.3V, RX, TX, GND)

	Update firmware instructions
	============================
	In the compiled,please gzip -d xxx.img.gz,then update firmware on uboot web.

Signed-off-by: Li Zhang <li.zhang@gl-inet.com>
[Copied dts file to files-5.4]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>