cbtable: remove chromeos_acpi from cbtable

Since we can derive chromeos_acpi's location from that of
ACPI GNVS, remove chromeos_acpi entry from cbtable and
instead use acpi_gnvs + GVNS_CHROMEOS_ACPI_OFFSET.

BUG=b:112288216
TEST=None
CQ-DEPEND=CL:1179725

Change-Id: I74d8a9965a0ed7874ff03884e7a921fd725eace9
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://review.coreboot.org/28190
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/vendorcode/google/chromeos/gnvs.h

@@ -41,6 +41,18 @@
 #define ACTIVE_ECFW_RO		0
 #define ACTIVE_ECFW_RW		1
 
+/*
+ * chromeos_acpi_t portion of ACPI GNVS is assumed to live at
+ * 0x100 - 0x1000.  When defining global_nvs_t, use check_member
+ * to ensure that it is properly aligned:
+ *
+ *   check_member(global_nvs_t, chromeos, GNVS_CHROMEOS_ACPI_OFFSET);
+ */
+#define GNVS_CHROMEOS_ACPI_OFFSET 0x100
+
+/* device_nvs_t is assumed to live directly after chromeos_acpi_t. */
+#define GNVS_DEVICE_NVS_OFFSET 0x1000
+
 typedef struct {
 	/* ChromeOS specific */
 	u32	vbt0;		// 00 boot reason