debian/control: Recommend installation of osmo-mgw

osmo-msc is pretty useless without osmo-mgw these days.  Let's not
make it a strong dependency, as the mgw could of course be running
on different machines.

Change-Id: I76c1bf30c733cf2fd596a8971ccb8bac4220be66
diff --git a/debian/control b/debian/control
index 0f3da25..9a85589 100644
--- a/debian/control
+++ b/debian/control
@@ -33,6 +33,7 @@
 Architecture: any
 Multi-Arch: foreign
 Depends: ${misc:Depends}, ${shlibs:Depends}, libdbd-sqlite3
+Recommends: osmo-mgw
 Description: OsmoMSC: Osmocom's Mobile Switching Center for 2G and 3G circuit-switched mobile networks
   The Mobile Switching Center (MSC) is the heart of 2G/3G
   circuit-switched services.  It terminates the A-interface links from the