PCI/IA64: introduce probe_pci_root_info() to manage _CRS resource

Currently, initialize _CRS resource code in IA64 make pci_acpi_scan_root()
some lengthiness. Introduce probe_pci_root_info() to manage it like in X86,

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-ia64@vger.kernel.org
Signed-off-by: Tony Luck <tony.luck@intel.com>