misc: Add simple driver for some Nuvoton NCT6102D devices

This simple driver provides some functions to control some of the
integrated devices. The watchdog is enabled per default. This driver
adds a function to disable the watchdog. Also the internal legacy
UART (io address 0x3f8/0x2f8) is enabled per default.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Cc: Simon Glass <sjg@chromium.org>