PCI: dwc: Make hisi_pcie_platform_ops static

Fix the following sparse warning:

drivers/pci/controller/dwc/pcie-hisi.c:365:21: warning:
symbol 'hisi_pcie_platform_ops' was not declared. Should it be static?

Link: https://lore.kernel.org/r/1587611883-26960-1-git-send-email-zou_wei@huawei.com


Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Zhou Wang <wangzhou1@hisilicon.com>