Add support for Moxa UC-8100-ME-T open platform

The UC-8100-ME-T computing platform is designed
for embedded data acquisition industrial applications

The features of UC-8100-ME-T series are:
* eMMC
* SPI flash
* SD slot
* 2x LAN
* 2 RS-232/422/485 ports, software-selectable
* Mini PCIe form factor with USB signal
* USB host
* EEPROM
* TPM
* Watchdog
* RTC
* User gpio-keys
* User LEDs
* User button
Signed-off-by: SZ Lin <sz.lin@moxa.com>
Acked-by: Rob Herring <robh@kernel.org>
[tony@atomide.com: fix unit adress as suggested by Rob]
Signed-off-by: Tony Lindgren <tony@atomide.com>