mb/google/octopus/variants/phaser: Implement variant_memory_sku()

This change override memory ID 3 to 1 to workaround the incorrect
memory straps in hardware.
We would use board_id 7 to identify the specific boards which need
to correct the memory ID.

BUG=b:259301885
BRANCH=Octopus
TEST=Verified on Phaser

Signed-off-by: Joey Peng <joey.peng@lcfc.corp-partner.google.com>
Change-Id: I2330b7e16a09f8cc76ed96e81a6165afa80a03a4
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70353
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Derek Huang <derekhuang@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Henry Sun <henrysun@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/octopus/variants/phaser/Makefile.inc

@@ -1,5 +1,7 @@
 bootblock-y += gpio.c
 
+romstage-y += memory.c
+
 ramstage-y += variant.c
 ramstage-y += gpio.c
 ramstage-y += mainboard.c

src/mainboard/google/octopus/variants/phaser/memory.c

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <baseboard/variants.h>
+#include <boardid.h>
+#include <gpio.h>
+#include <variant/gpio.h>
+
+size_t variant_memory_sku(void)
+{
+	size_t rt;
+	gpio_t pads[] = {
+		[3] = MEM_CONFIG3, [2] = MEM_CONFIG2,
+		[1] = MEM_CONFIG1, [0] = MEM_CONFIG0,
+	};
+
+	rt = gpio_base2_value(pads, ARRAY_SIZE(pads));
+
+	if (board_id() == 7)
+		return (rt == 3) ? 1 : rt;  // If RAM ID = 3, return 1
+	else
+		return rt;
+}