systemd: depend on networking-online.target

Related: SYS#6400
Change-Id: Ifbac18a38e086e42c67499b7818cdf08629d0000
diff --git a/contrib/systemd/osmo-pcu.service b/contrib/systemd/osmo-pcu.service
index 94616e3..5324883 100644
--- a/contrib/systemd/osmo-pcu.service
+++ b/contrib/systemd/osmo-pcu.service
@@ -1,5 +1,7 @@
 [Unit]
 Description=Osmocom osmo-pcu
+After=network-online.target
+Wants=network-online.target
 
 [Service]
 Type=simple