VT: do not remove a rx session even if ECONNREFUSED occurred.

[Problem] rx session removed if recvfrom() returned
 -1 with ECONNREFUSED reason.
[Cause] ECONNREFUSED can be occurred while calling
  recvfrom() after sendto() for a rtcp packet such
  as RR and TMMBR if remote side didn't open a socket yet.
[Solution] rx session should not be removed even if
  remote device didn't ready to receive a packet yet.

Bug: 196252321

Change-Id: I22b1fbd660a930aaac5e0952fb81cf0537822b77
Signed-off-by: Gaurav <gaurav.tiw@samsung.com>