mb/google/dedede/var/cappy2: Generate SPD ID for supported memory parts

Add supported memory 'K4U6E3S4AA-MGCR' for cappy2

BUG=None
TEST=Build the cappy2 board.

Signed-off-by: Sunwei Li <lisunwei@huaqin.corp-partner.google.com>
Change-Id: Ie76a4dca607bb2c3261bbe5478209a43e8430591
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56514
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>

src/mainboard/google/dedede/variants/cappy2/memory/Makefile.inc

@@ -1,5 +1,5 @@
 ## SPDX-License-Identifier: GPL-2.0-or-later
 ## This is an auto-generated file. Do not edit!!
-## Add memory parts in mem_parts_used.txt and run spd_tools to regenerate.
 
-SPD_SOURCES = placeholder.spd.hex
+SPD_SOURCES =
+SPD_SOURCES += lp4x-spd-1.hex      # ID = 0(0b0000)  Parts = K4U6E3S4AA-MGCR

src/mainboard/google/dedede/variants/cappy2/memory/dram_id.generated.txt

@@ -1 +1,2 @@
 DRAM Part Name                 ID to assign
+K4U6E3S4AA-MGCR                0 (0000)

src/mainboard/google/dedede/variants/cappy2/memory/mem_parts_used.txt

@@ -9,3 +9,4 @@
 # See util/spd_tools/{ddr4,lp4x}/README.md for more details and instructions.
 
 # Part Name
+K4U6E3S4AA-MGCR