util: add smmstoretool for editing SMMSTORE

Offline SMMSTORE variable modification tool.  Can be used to
pre-configure ROM image or debug EFI state stored in a dump.

Change-Id: I6c1c06f1d0c39c13b5be76a3070f09b715aca6e0
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79080
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

util/smmstoretool/storage.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef SMMSTORETOOL__STORAGE_H__
+#define SMMSTORETOOL__STORAGE_H__
+
+#include "vs.h"
+#include "utils.h"
+
+struct storage_t {
+	bool rw;
+	struct mem_range_t file;
+	struct mem_range_t store_area;
+	struct var_store_t vs;
+};
+
+bool storage_open(const char store_file[], struct storage_t *storage, bool rw);
+
+bool storage_write_back(struct storage_t *storage);
+
+void storage_drop(struct storage_t *storage);
+
+#endif // SMMSTORETOOL__STORAGE_H__