mb/intel/harcuvar: Fix board_id() return type

The weak definition of board_id() in coreboot_table.c returns a
uint32_t, so update this function to match. This fixes a compiler error
when using LTO.

Change-Id: I6ad03ecedcf4a4d9f0c917cdc760f81ddde06d11
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39015
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: David Guckian
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/mainboard/intel/harcuvar/romstage.c b/src/mainboard/intel/harcuvar/romstage.c
index a5c1327..542f81e 100644
--- a/src/mainboard/intel/harcuvar/romstage.c
+++ b/src/mainboard/intel/harcuvar/romstage.c
@@ -88,7 +88,7 @@
 {
 	size_t num;
 	const struct dnv_pad_config *table;
-	uint8_t boardid = board_id();
+	uint32_t boardid = board_id();
 
 	/* Configure pads prior to SiliconInit() in case there's any
 	* dependencies during hardware initialization.