sw64: pci: remove some useless code

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56OLG



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pci_probe_only makes no sense because it's always false.

Signed-off-by: Zhou Xuemei <zhouxuemei@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>