lotso: Update board type to BOARD_TYPE_ULT_ULX

Update board type to BOARD_TYPE_ULT_ULX

BUG=b:348147663
BRANCH=none
TEST=Built and compare the results of
command 'dmidecode --type 17 | grep Speed'

[Before]
  Speed: 8400 MT/s
  Configured Memory Speed: 6400 MT/s
[After]
  Speed: 8400 MT/s
  Configured Memory Speed: 5200 MT/s

Change-Id: I049d7c19424f41e83480f4b80bafd6ef8b9e30f6
Signed-off-by: Kun Liu <liukun11@huaqin.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83191
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Shelley Chen <shchen@google.com>
Reviewed-by: Jian Tong <tongjian@huaqin.corp-partner.google.com>

src/mainboard/google/brox/variants/lotso/memory.c

@@ -3,6 +3,7 @@
 #include <baseboard/gpio.h>
 #include <baseboard/variants.h>
 #include <gpio.h>
+#include <soc/romstage.h>
 
 static const struct mb_cfg baseboard_memcfg = {
 	.type = MEM_TYPE_LP5X,
@@ -64,6 +65,8 @@ static const struct mb_cfg baseboard_memcfg = {
 	.LpDdrDqDqsReTraining = 1,
 
 	.ect = 1, /* Early Command Training */
+
+	.UserBd = BOARD_TYPE_ULT_ULX,
 };
 
 const struct mb_cfg *variant_memory_params(void)