vsc_sum_crc
cmd->data.dl_start.crc = cpu_to_le32(vsc_sum_crc(cmd, c_len));
cmd->data.dl_set.payload[index] = cpu_to_le32(vsc_sum_crc(cmd, c_len));
cmd->data.dl_start.crc = cpu_to_le32(vsc_sum_crc(cmd, c_len));
cmd->data.boot.crc = cpu_to_le32(vsc_sum_crc(cmd, c_len));