vty 'show connection': show msc_a->via_cell instead of vsub->cgi

For 'show subscriber cache', we print vsub->cgi. For 'show connection', it
makes more sense to print msc_a->via_cell.

This is tested by osmo-ttcn3-hacks Ie410714a96353f74a52a104c56fa0a08683e0004.

Related: OS#4627
Change-Id: I194271af2acb37b4f8cc2d106ab2fd2b0d443589

src/libmsc/msc_vty.c

@@ -911,7 +911,7 @@ static void vty_dump_one_conn(struct vty *vty, const struct msub *msub,
 
 	if (vsub) {
 		MSC_VTY_DUMP(vty, offset, "LAC / cell ID: %u / %u%s",
-			     vsub->cgi.lai.lac, vsub->cgi.cell_identity,
+			     msc_a->via_cell.lai.lac, msc_a->via_cell.cell_identity,
 			     VTY_NEWLINE);
 	}