mb/purism/librem_skl: Fix pcie_rp5 in device tree (WLAN)

WLAN has always been pcie_rp5, there is nothing on pcie_rp1.  RP5 gets
promoted to function 0 (RP1's function) since no earlier functions are
enabled.

This simplifies later refactoring that will handle the FSP root port
enable flags (which were correctly set already) using the device tree
enables.

Test: Boot librem_13v2 and verify WLAN is enabled.

Change-Id: I7a724a01b5f171a16de83ff6122630e2d66557c1
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80065
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
diff --git a/src/mainboard/purism/librem_skl/devicetree.cb b/src/mainboard/purism/librem_skl/devicetree.cb
index 1928d15..08a88d6 100644
--- a/src/mainboard/purism/librem_skl/devicetree.cb
+++ b/src/mainboard/purism/librem_skl/devicetree.cb
@@ -157,7 +157,7 @@
 		device ref south_xdci	on  end
 		device ref thermal	on  end
 		device ref sata		on  end
-		device ref pcie_rp1	on  end
+		device ref pcie_rp5	on  end
 		device ref pcie_rp9	on  end
 		device ref lpc_espi	on
 			chip drivers/pc80/tpm