[ip6] do not report an error for disabled host loopback

Currently, sending an IPv6 multicast destined packet encoded in
otMessage with the otIp6Send() function reports an error kErrorNoRoute
if "host loopback allowed" flag is disabled (despite of packet being
properly passed to Mesh Forwarder). This commit changes a flag checking
statement to return kErrorNone instead.

Signed-off-by: Konrad Derda <[email protected]>

src/core/net/ip6.cpp

@@ -935,7 +935,7 @@ Error Ip6::PassToHost(OwnedPtr<Message> &aMessagePtr,
     Error             error = kErrorNone;
     OwnedPtr<Message> messagePtr;
 
-    VerifyOrExit(aMessagePtr->IsLoopbackToHostAllowed(), error = kErrorNoRoute);
+    VerifyOrExit(aMessagePtr->IsLoopbackToHostAllowed());
 
     VerifyOrExit(mReceiveIp6DatagramCallback.IsSet(), error = kErrorNoRoute);