arm64: dts: bst: add support for Black Sesame Technologies C1200 CDCU1.0 board

arm64: dts: bst: add support for Black Sesame Technologies C1200 CDCU1.0 board

Add device tree support for the Black Sesame Technologies (BST) C1200
CDCU1.0 ADAS 4C2G platform. This platform is based on the BST C1200 SoC
family.
The changes include:
- Adding a new BST device tree directory
- Adding Makefile entries to build the BST platform device trees
- Adding the device tree for the BST C1200 CDCU1.0 ADAS 4C2G board
This board features a quad-core Cortex-A78 CPU, and various peripherals
including UART, and interrupt controller.

Signed-off-by: Albert Yang <yangzh0906@thundersoft.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>