PCI: hisi: Include register block base in PCIE_SYS_STATE4 address

Include the PCIE_HIP06_CTRL_OFF block base in the PCIE_SYS_STATE4 register
address so reads of PCIE_SYS_STATE4 don't have to mention both.  No
functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>