arm64: dts: imx8mm: Add Gateworks i.MX 8M Mini Development Kits

The Gateworks Venice GW71xx-0x/GW72xx-0x/GW73xx-0x are development
kits consisting of a GW700x SoM and a Baseboard. Future SoM's such
as the GW701x will create additional combinations.

The GW700x SoM contains:
- i.MX 8M Mini SoC
- LPDDR4 DRAM
- eMMC FLASH
- Gateworks System Controller (eeprom/pushbutton/reset/voltage-monitor)
- GbE PHY connected to the i.MX 8M Mini FEC
- Power Management IC

The GW71xx Baseboard contains:
- 1x MiniPCIe Socket with USB2.0, PCIe, and SIM
- 1x RJ45 GbE (i.MX 8M Mini FEC)
- I/O connector with 1x-SPI/1x-I2C/1x-UART/4x-GPIO signals
- PCIe Clock generator
- GPS and accelerometer
- 1x USB 2.0 Front Panel connector
- wide range power supply

The GW72xx Baseboard contains:
- 2x MiniPCIe Socket with USB2.0, PCIe, and SIM
- 2x RJ45 GbE (i.MX 8M Mini FEC and LAN743x)
- 1x MicroSD connector
- 1x USB 2.0 Front Panel connector
- 1x SPI connector
- 1x Serial connector supporting 2x-UART or 1x-UART configured as 1 of:
RS232 w/ flow-control, RS485, RS422
- PCIe Clock generator
- GPS and accelerometer
- Media Expansion connector (MIPI-CSI/MIPI-DSI/GPIO/I2S)
- I/O connector with 2x-ADC,2x-GPIO,1x-UART,1x-I2C
- wide range power supply

The GW73xx Baseboard contains:
- 3x MiniPCIe Socket with USB2.0, PCIe, and SIM
- 2x RJ45 GbE (i.MX 8M Mini FEC and LAN743x)
- 1x MicroSD connector
- 1x USB 2.0 Front Panel connector
- 1x SPI connector
- 1x Serial connector supporting 2x-UART or 1x-UART configured as 1 of:
RS232 w/ flow-control, RS485, RS422
- WiFi/BT
- PCIe Clock generator
- GPS and accelerometer
- Media Expansion connector (MIPI-CSI/MIPI-DSI/GPIO/I2S)
- I/O connector with 2x-ADC,2x-GPIO,1x-UART,1x-I2C
- wide range power supply

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>