lib: Rename string.x to sbi_string.x

All string functions are part of libsbi. It makes more sense
to rename them to sbi_string.x as the libsbi can be linked
with external libraries that can have similar implementation.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Acked-by: Anup Patel <anup.patel@wdc.com>

include/sbi/sbi_string.h

@@ -0,0 +1,39 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Atish Patra <atish.patra@wdc.com>
+ */
+
+#ifndef __STRING_H__
+#define __STRING_H__
+
+#include <sbi/sbi_types.h>
+
+int sbi_strcmp(const char *a, const char *b);
+
+size_t sbi_strlen(const char *str);
+
+size_t sbi_strnlen(const char *str, size_t count);
+
+char *sbi_strcpy(char *dest, const char *src);
+
+char *sbi_strncpy(char *dest, const char *src, size_t count);
+
+char *sbi_strchr(const char *s, int c);
+
+char *sbi_strrchr(const char *s, int c);
+
+void *sbi_memset(void *s, int c, size_t count);
+
+void *sbi_memcpy(void *dest, const void *src, size_t count);
+
+void *sbi_memmove(void *dest, const void *src, size_t count);
+
+int sbi_memcmp(const void *s1, const void *s2, size_t count);
+
+void *sbi_memchr(const void *s, int c, size_t count);
+
+#endif