spapr: Fix failure path for attempting to hot unplug PCI bridges

For various technical reasons we can't currently allow unplug a PCI to PCI
bridge on the pseries machine.  spapr_pci_unplug_request() correctly
generates an error message if that's attempted.

But.. if the given errp is not error_abort or error_fatal, it doesn't
actually stop trying to unplug the bridge anyway.

Fixes: 14e714900f6b "spapr: Allow hot plug/unplug of PCI bridges and devices under PCI bridges"
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 709a527..55ca9de 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1663,6 +1663,7 @@
 
         if (pc->is_bridge) {
             error_setg(errp, "PCI: Hot unplug of PCI bridges not supported");
+            return;
         }
 
         /* ensure any other present functions are pending unplug */