Make pci_claim_resource() use request_resource() rather than insert_resource()

This function has traditionally used "insert_resource()", because before
commit cebd78a8c5 ("Fix pci_claim_resource") it used to just insert the
resource into whatever root resource tree that was indicated by
"pcibios_select_root()".

So there Matthew fixed it to actually look up the proper parent
resource, which means that now it's actively wrong to then traverse the
resource tree any more: we already know exactly where the new resource
should go.

And when we then did commit a76117dfd6 ("x86: Use pci_claim_resource"),
which changed the x86 PCI code from the open-coded

pr = pci_find_parent_resource(dev, r);
if (!pr || request_resource(pr, r) < 0) {

to using

if (pci_claim_resource(dev, idx) < 0) {

that "insert_resource()" now suddenly became a problem, and causes a
regression covered by

http://bugzilla.kernel.org/show_bug.cgi?id=13891

which this fixes.

Reported-and-tested-by: Rafael J. Wysocki <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Andrew Patterson <[e-mail]>
Cc: Linux PCI <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/pci/setup-res.c

···
 {
 	struct resource *res = &dev->resource[resource];
 	struct resource *root;
-	char *dtype = resource < PCI_BRIDGE_RESOURCES ? "device" : "bridge";
 	int err;
 
 	root = pci_find_parent_resource(dev, res);
 
 	err = -EINVAL;
 	if (root != NULL)
-		err = insert_resource(root, res);
+		err = request_resource(root, res);
 
 	if (err) {
+		const char *dtype = resource < PCI_BRIDGE_RESOURCES ? "device" : "bridge";
 		dev_err(&dev->dev, "BAR %d: %s of %s %pR\n",
 			resource,
 			root ? "address space collision on" :