Fix: report UST consumer channel creation error

The session daemon reports no error whatsoever when the consumer daemon
fails to create a channel. We don't want to print errors when failing to
send the channel to the UST application though, because the application
may be concurrently exiting. So only print those errors when receiving
reply from the consumerd.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>