frv/PCI: Use pci_claim_resource

Instead of open-coding pci_find_parent_resource and request_resource,
just call pci_claim_resource.

Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>