platform: Add support for Shakti C-class SoC from IIT-M

C-Class is a member of the SHAKTI family of processors from Indian
Institute of Technology - Madras(IIT-M).
It is an extremely configurable and commercial-grade 5-stage in-order
core supporting the standard RV64GCSUN ISA extensions.

https://gitlab.com/shaktiproject/cores/c-class/blob/master/README.md

We add OpenSBI support for Shakti C-class SoC.

Signed-off-by: Vijai Kumar K <vijai@behindbytes.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>

include/sbi_utils/serial/shakti-uart.h

@@ -0,0 +1,18 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Vijai Kumar K <vijai@behindbytes.com>
+ */
+
+#ifndef __SERIAL_SHAKTI_UART_H__
+#define __SERIAL_SHAKTI_UART_H__
+
+#include <sbi/sbi_types.h>
+
+void shakti_uart_putc(char ch);
+
+int shakti_uart_getc(void);
+
+int shakti_uart_init(unsigned long base, u32 in_freq, u32 baudrate);
+
+#endif