samples: net: zperf: Refactor udp_received

Use the state machine states to determine if the session has ended.
This way zperf will properly reply stat packet to remote client even if
duration of the session is non zero.

Also we don't need to update counter (received packet number) at end of
the session.

Note: if id < 0, it means session end, otherwise it's session ongoing.
(id is the first feild of application data from remote client).

Signed-off-by: Bub Wei <bub.wei@unisoc.com>
1 file changed