firmware: dmi_scan: Always show system identification string

Let's keep consistent when print dmi_ids_string between SMBIOS 2.x
and SMBIOS 3.x, and always show the system identification string,
like Vendor, Product/Board name and BIOS infos.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>