arm64: dts: aspeed: Add initial AST27xx SoC device tree

arm64: dts: aspeed: Add initial AST27xx SoC device tree

Add initial device tree support for the ASPEED AST27xx family, the
8th-generation Baseboard Management Controller (BMC) SoCs.

AST27xx SOC Family
 - https://www.aspeedtech.com/server_ast2700/
 - https://www.aspeedtech.com/server_ast2720/
 - https://www.aspeedtech.com/server_ast2750/

The AST27xx features a dual-SoC architecture consisting of two dies,
referred to as SoC0 and SoC1 - interconnected through an internal
proprietary bus. Both SoCs share the same address decoding scheme,
while each maintains independent clock and reset domains.

- SoC0 (CPU die): contains a quad-core Cortex-A35 cluster and two
  Cortex-M4 cores, along with high-speed peripherals.
- SoC1 (I/O die): includes the BootMCU (responsible for system
  boot) and its own clock/reset domains low-speed peripherals.

The device tree describes the SoC0 and SoC1 domains and their peripheral
layouts.

Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
Link: https://lore.kernel.org/r/20260609-upstream_ast2700-v9-3-f631752f0cb1@aspeedtech.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>