PCI: iproc: Free resource list after registration

The resource list is only used in the setup process and was never freed.
pci_add_resource() allocates a memory area to store the list item.

Fix the memory leak.

Tested-by: Ray Jui <rjui@broadcom.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>