hw/smbios: Fix OEM strings table option validation

hw/smbios: Fix OEM strings table option validation

qemu_smbios_type11_opts did not have the list terminator and that
resulted in out-of-bound memory access. It also needs to have an element
for the type option.

Cc: qemu-stable@nongnu.org
Fixes: 2d6dcbf93fb0 ("smbios: support setting OEM strings table")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>