firmware: dmi: Add access to the SKU ID string

This is used in some systems from user space for determining the identity
of the device.

Expose this as a file so that that user-space tools don't need to read
from /sys/firmware/dmi/tables/DMI

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 54e66ad..f248354 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -447,6 +447,7 @@ static void __init dmi_decode(const struct dmi_header *dm, void *dummy)
 		dmi_save_ident(dm, DMI_PRODUCT_VERSION, 6);
 		dmi_save_ident(dm, DMI_PRODUCT_SERIAL, 7);
 		dmi_save_uuid(dm, DMI_PRODUCT_UUID, 8);
+		dmi_save_ident(dm, DMI_PRODUCT_SKU, 25);
 		dmi_save_ident(dm, DMI_PRODUCT_FAMILY, 26);
 		break;
 	case 2:		/* Base Board Information */