sw64: pci: fix maximum bus number for pci scan

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GDR1



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When PCI devices enable SRIOV function, the previous policy that uses
pci_find_bus to locate PCI bus from a given domain and bus number may
return false PCI bus number, so this patch fixes this patch.

Signed-off-by: Yang Qiang <yangqiang@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>