PCI: Don't rely on of_platform_depopulate() for reused OF-nodes

PCI: Don't rely on of_platform_depopulate() for reused OF-nodes

of_platform_depopulate() doesn't play nicely with reused OF nodes - it
ignores the ones that are not marked explicitly as populated and it may
happen that the PCI device goes away before the platform device in which
case the PCI core clears the OF_POPULATED bit.

Unconditionally unregister the platform devices for child nodes when
stopping the PCI device.

Link: https://lore.kernel.org/r/20240823093323.33450-2-brgl@bgdev.pl
Fixes: 8fb18619d910 ("PCI/pwrctl: Create platform devices for child OF nodes of the port node")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>