PCI: dwc: histb: Use pci_ops for root config space accessors

Now that DWC drivers can setup their own pci_ops for the root and child
buses, convert the HiSilicon histb driver to use the standard pci_ops
for root bus config accesses.

Link: https://lore.kernel.org/r/20200821035420.380495-12-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>