dts: bindings: Add T-Head C906 CPU

C906 is a RISC-V CPU designed by T-Head. This commit introduces its DTS
binding for later use.

Signed-off-by: Chen Xingyu <[email protected]>

Author: xingrz

dts/bindings/cpu/thead,c906.yaml

@@ -0,0 +1,8 @@
+# Copyright (c) 2023-2024 Chen Xingyu <[email protected]>
+# SPDX-License-Identifier: Apache-2.0
+
+description: T-Head C906 RISC-V CPU
+
+compatible: "thead,c906"
+
+include: riscv,cpus.yaml