auto upgrade hlr.db in the service file

Change-Id: Icd3af5160e6d8f31fed5e84055fbb09322c54c2b
diff --git a/contrib/systemd/osmo-hlr.service b/contrib/systemd/osmo-hlr.service
index 2eea0c4..9649d42 100644
--- a/contrib/systemd/osmo-hlr.service
+++ b/contrib/systemd/osmo-hlr.service
@@ -5,7 +5,7 @@
 [Service]
 Type=simple
 Restart=always
-ExecStart=/usr/bin/osmo-hlr -c /etc/osmocom/osmo-hlr.cfg -l /var/lib/osmocom/hlr.db
+ExecStart=/usr/bin/osmo-hlr -U -c /etc/osmocom/osmo-hlr.cfg -l /var/lib/osmocom/hlr.db
 RestartSec=2
 
 [Install]