sql/Makefile: Install sql files under doc/.../sql subdir

Change-Id: I1c9008d4692412a0cfe39d05216fc9c857cf1e8a
diff --git a/debian/osmo-hlr.install b/debian/osmo-hlr.install
index 1e3bbc6..825e65c 100644
--- a/debian/osmo-hlr.install
+++ b/debian/osmo-hlr.install
@@ -1,4 +1,5 @@
 /usr/bin/osmo-hlr
 /usr/bin/osmo-hlr-db-tool
-/usr/share/doc/osmo-hlr/hlr.sql
+/usr/share/doc/osmo-hlr/sql/hlr.sql
+/usr/share/doc/osmo-hlr/sql/hlr_data.sql
 /usr/share/doc/osmo-hlr/examples/osmo-hlr.cfg