mb/google/sarien: Set SMBIOS mainboard SKU

Setting sku_id() is not enough to get a value to show up in the SMBIOS
tables, it also needs to be returned as a string for the table creation
to consume.  This change defines the smbios_mainboard_sku() function
and returns a string constant of "sku#" as expected.

Change-Id: I03013bab89d53d1eba969c6ffb7e95fcbb315a81
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://review.coreboot.org/29649
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Trent Begin <tbegin@google.com>

src/mainboard/google/sarien/sku.c

@@ -14,9 +14,15 @@
  */
 
 #include <boardid.h>
+#include <smbios.h>
 #include <variant/variant.h>
 
 uint32_t sku_id(void)
 {
 	return VARIANT_SKU_ID;
 }
+
+const char *smbios_mainboard_sku(void)
+{
+	return VARIANT_SKU_NAME;
+}

src/mainboard/google/sarien/variants/arcada/include/variant/variant.h

@@ -18,5 +18,6 @@
 
 /* Arcada is SKU ID 2 */
 #define VARIANT_SKU_ID	2
+#define VARIANT_SKU_NAME "sku2"
 
 #endif

src/mainboard/google/sarien/variants/sarien/include/variant/variant.h

@@ -18,5 +18,6 @@
 
 /* Sarien is SKU ID 1 */
 #define VARIANT_SKU_ID	1
+#define VARIANT_SKU_NAME "sku1"
 
 #endif