google/kahlee: Add PSP to devicetree.cb

Add the missing device and ensure it shows up in the devicetree prior
to PCI enumeration.

Change-Id: Ia2c4ba1200422b36c533e86065a4fcd10c4b2722
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/22055
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/kahlee/devicetree.cb

@@ -34,6 +34,7 @@ chip soc/amd/stoneyridge
 		device pci 2.4 on  end # x1 PCIe slot
 		device pci 2.5 on  end # Cardreader
 		# devices on the NB/SB Link, but on the same pci bus
+		device pci 8.0 on  end # PSP
 		device pci 9.0 on  end # PCIe Host Bridge
 		device pci 9.2 on  end # HDA
 		device pci 10.0 on  end # xHCI