dog/vdi: replace strtoll with strtoull

oid is of uint64_t type, VDI object oid is started with 0x80,
which is large than the maximum of long long int. So, we should
replace strtoll with strtoull in function vdi_parser().

Signed-off-by: Bingpeng Zhu <bingpeng.zbp@alibaba-inc.com>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>