security/memory: Clear memory in ramstage

* Add architecture independend way of clearing all DRAM
* Implemented in ramstage as MTRRs need to be set to speed up
  clearing. Takes up to 15 seconds per GiB otherwise.
* Use memset_pae on x86
* Add quirks for FSP1.0

Tested on P8H61M-Pro:
* Clears 4GiB in less than 1 second
Tested on wedge100s:
* Clears 8GiB in 2 seconds

Change-Id: Idaadb8fb438e5b95557c0f65a14534e8762fde20
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31550
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/include/arch/memory_clear.h

@@ -0,0 +1,24 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2019 9elements Agency GmbH
+ * Copyright (C) 2019 Facebook Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef MEMORY_CLEAR_H
+#define MEMORY_CLEAR_H
+
+#include <memrange.h>
+
+int arch_clear_memranges(const struct memranges *mem_reserved);
+
+#endif /* MEMORY_CLEAR_H */