mb/google/brox: Enable FSP UPD LpDdrDqDqsReTraining

FSP default value for LpDdrDqDqsReTraining is 1. For boards
that didn't set LpDdrDqDqsReTraining to any value, 0 was being
assigned and it caused black screen issue.

BUG=b:311450057
BRANCH=NONE
TEST=emerge-brox coreboot

Change-Id: I4a009076e50408a4f7ff16ddc96a0f2e47b09470
Signed-off-by: Ivy Jian <ivy.jian@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79646
Reviewed-by: Shelley Chen <shchen@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>

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

@@ -61,6 +61,8 @@ static const struct mb_cfg baseboard_memcfg = {
 		.ccc_config = 0x99,
 	},
 
+	.LpDdrDqDqsReTraining = 1,
+
 	.ect = 1, /* Early Command Training */
 
 };