pci: clean up of pci_default_read_config. This patch cleans up pci_default_read_config() removing ugly length and range check. Suggested by "Michael S. Tsirkin" <mst@redhat.com> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>