Debian: Don't package osmo-bsc_nat

We don't want to pacakge osmo-bsc_nat from osmo-bsc.git at this
point yet.  It only suports SCCPlite, which is not yet fully supported
by osmo-bsc.

Rather, we continue to package osmo-bsc_nat from openbsc.git like we did
so far.

Also, the osmo-bsc_nat binary really doesn't belong into the osmo-bsc
package at all.

Change-Id: Icf0bf80d61141ec060b6d2efcf3e65e2ef1ac2d6
diff --git a/debian/osmo-bsc.install b/debian/osmo-bsc.install
index cce0f65..abae32f 100644
--- a/debian/osmo-bsc.install
+++ b/debian/osmo-bsc.install
@@ -1,2 +1,2 @@
-usr/bin
+usr/bin/osmo-bsc
 usr/share/doc/osmo-bsc/examples/osmo-bsc