powerpc/pci: Add shutdown hook to pci_controller_ops

Currently pnv_pci_shutdown() calls the PHB shutdown code for all PHBs in the
system.  It dereferences the private_data assuming it's a powernv PHB, which
won't be the case when we have different PHB in the systems (like when we add
vPHBs for CXL).

This moves the shutdown hook to the pci_controller_ops and fixes the call site
to use that instead.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index 8a557b5..3c35487 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -704,12 +704,9 @@
 {
 	struct pci_controller *hose;
 
-	list_for_each_entry(hose, &hose_list, list_node) {
-		struct pnv_phb *phb = hose->private_data;
-
-		if (phb && phb->shutdown)
-			phb->shutdown(phb);
-	}
+	list_for_each_entry(hose, &hose_list, list_node)
+		if (hose->controller_ops.shutdown)
+			hose->controller_ops.shutdown(hose);
 }
 
 /* Fixup wrong class code in p7ioc and p8 root complex */