mn10300/PCI: Use generic pci_mmap_resource_range()

This was setting vma->vm_flags |= VM_LOCKED. Not sure why...

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: David Howells <dhowells@redhat.com>