xen: Port Xen grant table driver from mini-os

Make required updates to run on u-boot.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>

include/xen/gnttab.h

@@ -0,0 +1,24 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * (C) 2006, Steven Smith <sos22@cam.ac.uk>
+ * (C) 2006, Grzegorz Milos <gm281@cam.ac.uk>
+ * (C) 2020, EPAM Systems Inc.
+ */
+#ifndef __GNTTAB_H__
+#define __GNTTAB_H__
+
+#include <xen/interface/grant_table.h>
+
+void init_gnttab(void);
+void fini_gnttab(void);
+
+grant_ref_t gnttab_alloc_and_grant(void **map);
+grant_ref_t gnttab_grant_access(domid_t domid, unsigned long frame,
+				int readonly);
+int gnttab_end_access(grant_ref_t ref);
+const char *gnttabop_error(int16_t status);
+
+void get_gnttab_base(phys_addr_t *gnttab_base, phys_size_t *gnttab_sz);
+
+#endif /* !__GNTTAB_H__ */