ptpclock: Allow at least 100ms delay between Sync/Follow_Up and Delay_Req/Delay_Resp...

ptpclock: Allow at least 100ms delay between Sync/Follow_Up and Delay_Req/Delay_Resp messages

It doesn't matter for measurement purposes whether receiving them takes
a while and various PTP servers are not prioritizing to send them,
causing them to be dropped unnecessarily and preventing proper
synchronization with such servers.

This is especially a problem if the RTTs in the network are very low
compared to the additional delay imposed by the server.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2161>