PCI: hisi: Add DT almost-ECAM support for Hip06/Hip07 host controllers

The PCIe controller in HiSilicon Hip06/Hip07 SoCs is not completely
ECAM-compliant.  It is non-ECAM only for the RC bus config space; for any
other bus underneath the root bus it does support ECAM access.

Add DT support for the almost-ECAM Hip06/Hip07 controllers.

[bhelgaas: drop dev->of_node test, driver name "hisi-pcie-almost-ecam"]
Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
Reviewed-by: Zhou Wang <wangzhou1@hisilicon.com>