util/spd_tools: Add AMD Mendocino (MDN) platform

This patch adds support for MDN platform to the spd_tools.
This change replaces SBR with MDN.

BUG=b:243337816
TEST=Able to generate SPD for LP5 DRAM part.

Signed-off-by: EricKY Cheng <ericky_cheng@compal.corp-partner.google.com>
Change-Id: If099af36de8a64e96fbfde32eaf15990f4b330c8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67105
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jon Murphy <jpmurphy@google.com>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Amanda Hwang <amanda_hwang@compal.corp-partner.google.com>

util/spd_tools/src/part_id_gen/part_id_gen.go

@@ -40,7 +40,7 @@ var supportedPlatforms = [...]string{
 	"JSL",
 	"PCO",
 	"CZN",
-	"SBR",
+	"MDN",
 	"MTL",
 }