hw/xen: Downgrade a xen_bus_realize() non-error to warning

xen_bus_realize() reports a failure to set up a watch as error, but it
doesn't treat it as one: it simply continues.  Report a warning
instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20250314143500.2449658-3-armbru@redhat.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

hw/xen/xen-bus.c

@@ -353,10 +353,9 @@ static void xen_bus_realize(BusState *bus, Error **errp)
             xs_node_watch(xenbus->xsh, node, key, xen_bus_backend_changed,
                           xenbus, &local_err);
         if (local_err) {
-            /* This need not be treated as a hard error so don't propagate */
-            error_reportf_err(local_err,
-                              "failed to set up '%s' enumeration watch: ",
-                              type[i]);
+            warn_reportf_err(local_err,
+                             "failed to set up '%s' enumeration watch: ",
+                             type[i]);
             local_err = NULL;
         }