Revert "hostnamed: prevent it from crashing if the chassis is unknown"

This reverts commit 95b015de38.

"bus: handle serialization of NULL strings" (cd6f997f71)
should fix this issue.

src/hostname/hostnamed.c

@@ -360,9 +360,6 @@ static int property_get_chassis(
         else
                 name = c->data[PROP_CHASSIS];
 
-        if(!name)
-                name = "";
-
         r = sd_bus_message_append(reply, "s", name);
         if (r < 0)
                 return r;