dpservice-dump proper timestamps

[PlagueCZ]

As indicated in dpservice-dump source, timestamps shown should come from dpservice-bin, not from the dump tool.

Given latest changes introducing packet timestamps for dpservice HA needs, this is now possible to implement without many changes.

[PlagueCZ]

This is actually not that easy to do without generating the timestamps on dpservice side.

Basically, to convert NIC timestamp to human-readable timestamp, there needs to be some heuristic to compute the relation between RTC_CLOCK and NIC clock. And this is not easily done in the secondary process.

Involving the primary one would solve this, but would bring some overhead, which I do not think is a good tradeoff for now.