[intfsorch] Fix bug for VRF existence check (sonic-net#882)

Skip non-existent VRF, not the opposite.

Signed-off-by: shikenghua <[email protected]>

Author: shikenghua

orchagent/intfsorch.cpp

@@ -297,7 +297,7 @@ void IntfsOrch::doTask(Consumer &consumer)
         sai_object_id_t vrf_id = gVirtualRouterId;
         if (!vrf_name.empty())
         {
-            if (m_vrfOrch->isVRFexists(vrf_name))
+            if (!m_vrfOrch->isVRFexists(vrf_name))
             {
                 it++;
                 continue;