riscv: nx25: include: Add header files to support RISC-V

Add header files for RISC-V.
Cache, ptregs, data type and other definitions are included.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Signed-off-by: Greentime Hu <green.hu@gmail.com>
diff --git a/arch/riscv/include/asm/config.h b/arch/riscv/include/asm/config.h
new file mode 100644
index 0000000..5f94eb0
--- /dev/null
+++ b/arch/riscv/include/asm/config.h
@@ -0,0 +1,13 @@
+/*
+ * Copyright (C) 2017 Andes Technology Corporation
+ * Rick Chen, Andes Technology Corporation <rick@andestech.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef _ASM_CONFIG_H_
+#define _ASM_CONFIG_H_
+
+#define CONFIG_LMB
+
+#endif