PCI: Let pcibios_root_bridge_prepare() access bridge->windows

When pci_register_host_bridge() is called, bridge->windows are already
available. However these windows are being moved temporarily from there.

To let pcibios_root_bridge_prepare() have access to these windows, move the
windows movement after calling this function. This is useful for the MIPS
ralink mt7621 platform so it can set up I/O coherence units and avoid
custom MIPS code in the mt7621 PCIe controller driver.

Link: https://lore.kernel.org/r/20211207104924.21327-2-sergio.paracuellos@gmail.com
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

Author: paraka

drivers/pci/probe.c

@@ -898,8 +898,6 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 
 	bridge->bus = bus;
 
-	/* Temporarily move resources off the list */
-	list_splice_init(&bridge->windows, &resources);
 	bus->sysdata = bridge->sysdata;
 	bus->ops = bridge->ops;
 	bus->number = bus->busn_res.start = bridge->busnr;
@@ -925,6 +923,8 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	if (err)
 		goto free;
 
+	/* Temporarily move resources off the list */
+	list_splice_init(&bridge->windows, &resources);
 	err = device_add(&bridge->dev);
 	if (err) {
 		put_device(&bridge->dev);