PCI: rockchip: Factor out rockchip_pcie_deinit_phys()

Factor out rockchip_pcie_deinit_phys() so it can be reused by
rockchip_pcie_suspend_noirq() and rockchip_pcie_remove().  No functional
change intended.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>