mn10300/PCI: convert to pci_scan_root_bus() for correct root bus resources

Convert from pci_scan_bus() to pci_scan_root_bus() and remove root bus
resource fixups.  This fixes the problem of "early" and "header" quirks
seeing incorrect root bus resources.

CC: David Howells <dhowells@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>