Install/enable/restart unit files with dh_installsystemd

debian/install

 uffd-socketmapd /usr/sbin/
-debian/contrib/uffd-socketmapd-postfix.service /usr/lib/systemd/system/
-debian/contrib/uffd-socketmapd-postfix.socket /usr/lib/systemd/system/
-debian/contrib/uffd-socketmapd-postfix.conf /etc/
+debian/uffd-socketmapd-postfix.conf /etc/
+debian/uffd-socketmapd-postfix.service /lib/systemd/system/
+debian/uffd-socketmapd-postfix.socket /lib/systemd/system/

debian/rules

 #!/usr/bin/make -f
 %:
 	dh $@
+
+override_dh_installsystemd:
+	dh_installsystemd -puffd-socketmapd uffd-socketmapd-postfix.socket uffd-socketmapd-postfix.service