mb/lenovo/t420s/devicetree.cb: Fix PCIe port definitions

The NEC uPD720200A USB 3.0 controller on the T420s is actually
connected to PCIe root port #5 on the PCH, not #7. Enable RP#5,
disable RP#7 and update comments accordingly.
Test=USB 3.0 controller shows in `lspci`

Change-Id: I21ac72fd5632e552bdcdbd573cf92b433ed545ff
Signed-off-by: Jake Mannens <jakem_5@hotmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40281
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/mainboard/lenovo/t420s/devicetree.cb b/src/mainboard/lenovo/t420s/devicetree.cb
index 2fde40f..1f794c1 100644
--- a/src/mainboard/lenovo/t420s/devicetree.cb
+++ b/src/mainboard/lenovo/t420s/devicetree.cb
@@ -84,9 +84,9 @@
 			device pci 1c.3 on
 				smbios_slot_desc "7" "3" "ExpressCard Slot" "8"
 			end # PCIe Port #4 ExpressCard
-			device pci 1c.4 off end # PCIe Port #5
+			device pci 1c.4 on end # PCIe Port #5 NEC Corporation uPD720200A USB 3.0 Host Controller
 			device pci 1c.5 off end # PCIe Port #6 Intel Gigabit Ethernet PHY (not PCIe)
-			device pci 1c.6 on end # PCIe Port #7 NEC Corporation uPD720200A USB 3.0 Host Controller
+			device pci 1c.6 off end # PCIe Port #7
 			device pci 1c.7 off end # PCIe Port #8
 			device pci 1d.0 on end # USB Enhanced Host Controller #1
 			device pci 1e.0 off end # PCI bridge