PCI: dw-rockchip: Fix PHY function call sequence in rockchip_pcie_phy_deinit()

The documentation for the phy_power_off() function explicitly says that it
must be called before phy_exit().

Hence, follow the same rule in rockchip_pcie_phy_deinit().

Fixes: 0e898eb8 ("PCI: rockchip-dwc: Add Rockchip RK356X host controller driver")
Signed-off-by: Diederik de Haas <didi.debian@cknow.org>
[mani: commit message change]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Cc: stable@vger.kernel.org	# v5.15+
Link: https://patch.msgid.link/20250417142138.1377451-1-didi.debian@cknow.org