Fix container name (sonic-net#146)

# Why I did it
supervisor conf used the wrong container name as telemetry.

# How I did it
Fix the container name.

# How to verify it
Kill critical process and check GNMI container.

dockers/docker-sonic-gnmi/supervisord.conf

@@ -13,7 +13,7 @@ events=PROCESS_STATE
 buffer_size=1024
 
 [eventlistener:supervisor-proc-exit-listener]
-command=/usr/bin/supervisor-proc-exit-listener --container-name telemetry
+command=/usr/bin/supervisor-proc-exit-listener --container-name gnmi
 events=PROCESS_STATE_EXITED,PROCESS_STATE_RUNNING
 autostart=true
 autorestart=false