support smbios

alloc buffer in fseg memory and fill it with smbios anchor and
tables which read from the fw_cfg, then check type0 table and
rebuild it if it's not exist.

mainly inspired by the seabios, and borrowed some code from it.

Reviewed-by: Ben Luo <luoben@linux.alibaba.com>
Signed-off-by: kaihuan.pkh <kaihuan.pkh@alibaba-inc.com>