nvme-pci: look for StorageD3Enable on companion ACPI device instead

The documentation around the StorageD3Enable property hints that it
should be made on the PCI device.  This is where newer AMD systems set
the property and it's required for S0i3 support.

So rather than look for nodes of the root port only present on Intel
systems, switch to the companion ACPI device for all systems.
David Box from Intel indicated this should work on Intel as well.

Link: https://lore.kernel.org/linux-nvme/YK6gmAWqaRmvpJXb@google.com/T/#m900552229fa455867ee29c33b854845fce80ba70
Link: https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/power-management-for-storage-hardware-devices-intro


Fixes: df4f9bc4 ("nvme-pci: add support for ACPI StorageD3Enable property")
Suggested-by: Liang Prike <Prike.Liang@amd.com>
Acked-by: Raul E Rangel <rrangel@chromium.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>