osmo-msc.spec.in: Use %config(noreplace) to retain current config file

Change-Id: I00c3152b774a826230a112eae93b0e7c4d4f4c7a
diff --git a/contrib/osmo-msc.spec.in b/contrib/osmo-msc.spec.in
index da6c0ba..c968d3e 100644
--- a/contrib/osmo-msc.spec.in
+++ b/contrib/osmo-msc.spec.in
@@ -114,6 +114,6 @@
 %{_bindir}/osmo-msc
 %{_unitdir}/%{name}.service
 %dir %{_sysconfdir}/osmocom
-%config %{_sysconfdir}/osmocom/osmo-msc.cfg
+%config(noreplace) %{_sysconfdir}/osmocom/osmo-msc.cfg
 
 %changelog