Add/Combine Broadwell Chromebooks using variant board scheme

Combine existing boards google/auron_paine and google/samus with new
ChromeOS devices auron_yuna, gandof and lulu, using their common
reference board (auron) as a base.

Chromium sources used:
firmware-yuna-6301.59.B 6ed8b9d [CHERRY-PICK: broadwell: Update to...]
firmware-gandof-6301.155.B 666f34f [gandof: modify power limiting for...]
firmware-lulu-6301.136.B 8811714 [lulu: update RAMID table]

Additionally, some minor cleanup/changes were made:
 - I2C devices set to use level (vs edge) interrupt triggering
 - HDA verb entries use simplified macro entry format
 - correct FADT table header version
 - remove unused ACPI device entries / .asl file(s)
 - clean up ACPI code (e.g., trackpad on Lulu)
 - adjust _CID for trackpad on Lulu in order to not load non-functional
    Windows driver (does not affect Linux)
 - remove unused header includes (multiple/various)
 - correct I2C addresses used for SMBIOS device entries
 - correct misc typos etc

The existing auron_paine samus boards are removed.

Variant setup modeled after google/slippy

Change-Id: I53436878d141715eb18b8ea5043d71e6e8728fe8
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/17917
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/google/auron/variant.h

@@ -0,0 +1,23 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * 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 VARIANT_H
+#define VARIANT_H
+
+#include <arch/io.h>
+#include <soc/romstage.h>
+
+int variant_smbios_data(device_t dev, int *handle, unsigned long *current);
+void variant_romstage_entry(struct romstage_params *rp);
+
+#endif