Program flow with invalid key src nexthop, so that rpf check fails

Agent reserves index 2, and this nexthop would never be programmed
in kernel. Whenever agent doesnt find a route for rpf check
this nexthop index would be used to program flow. Hence
removing the check for src nexthop.
Closes-bug:#1424942

Change-Id: I45841f20a749542a7fa0b488bfc5889e5c4d8a54
(cherry picked from commit a39f4ae)

dp-core/vr_flow.c

@@ -1071,14 +1071,6 @@ vr_flow_req_is_invalid(struct vrouter *router, vr_flow_req *req,
             return -EINVAL;
     }
 
-    /*
-     * for delete, we need not validate nh_index from incoming request
-     */
-    if (req->fr_flags & VR_FLOW_FLAG_ACTIVE) {
-        if (!__vrouter_get_nexthop(router, req->fr_src_nh_index))
-            return -EINVAL;
-    }
-
     return 0;
 }