libpldmresponder: pldm_bios_table_append_pad_checksum() is deprecated

Migrate to pldm_bios_table_append_pad_checksum_check() which does not
sanitize its behaviour with assert().

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Ide288bb40e5acabd2bf85870849bf176ddcbc621