systemd: Add a service for the sysmopcu

Provide a systemd service file for sysmopcu, leaves
the bundled combined sysvinit for sysmobts and sysmopcu
for legacy systems.

Sponsored-by: sysmocom

contrib/sysmopcu.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=sysmocom sysmoPCU
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/osmo-pcu -c /etc/osmocom/osmo-pcu.cfg
+Restart=always
+RestartSec=5
+
+# The msg queues must be read fast enough
+CPUSchedulingPolicy=rr
+CPUSchedulingPriority=1
+
+[Install]
+WantedBy=multi-user.target