acpi/gpex: Build tables for pxb

acpi/gpex: Build tables for pxb

The resources of pxbs are obtained by crs_build and the resources
used by pxbs would be moved from the resources defined for host-bridge.

The resources for pxb are composed of following two parts:
1. The bar space of the pci-bridge/pcie-root-port behined it
2. The config space of devices behind it.

Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Message-Id: <20201119014841.7298-6-cenjiahui@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>