PCI: imx6: Disable clocks in reverse order of enable

imx6_pcie_clk_enable() enables clocks in the order:

  pcie_phy
  pcie_bus
  pcie
  imx6_pcie_enable_ref_clk

Change imx6_pcie_clk_disable() to disable them in the reverse order.

Link: https://lore.kernel.org/r/1657783869-19194-16-git-send-email-hongxing.zhu@nxp.com


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Richard Zhu <hongxing.zhu@nxp.com>