riscv: cpu: cv1800b: Add support for cv1800b SoC

Add Sophgo cv1800b SoC to support RISC-V arch.

Signed-off-by: Kongyang Liu <seashell11234455@gmail.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/cpu/cv1800b/Makefile b/arch/riscv/cpu/cv1800b/Makefile
new file mode 100644
index 0000000..da12e0f
--- /dev/null
+++ b/arch/riscv/cpu/cv1800b/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (c) 2024, Kongyang Liu <seashell11234455@gmail.com>
+
+obj-y += dram.o
+obj-y += cpu.o