mb/clevo/cml-u: drop PcieRpSlotImplemented for card reader

PcieRpSlotImplemented should only be set to 1 for PCIe ports
implementing a PCIe slot. Drop it for the on-board card reader.

Change-Id: I22628b4d4a7e317a01e46a61b5cd7bb9ebf548a0
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45776
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by:  Felix Singer <felixsinger@posteo.net>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/mainboard/clevo/cml-u/variants/l140cu/devicetree.cb b/src/mainboard/clevo/cml-u/variants/l140cu/devicetree.cb
index 55c5c6e..e079dff 100644
--- a/src/mainboard/clevo/cml-u/variants/l140cu/devicetree.cb
+++ b/src/mainboard/clevo/cml-u/variants/l140cu/devicetree.cb
@@ -138,7 +138,6 @@
 			register "PcieRpLtrEnable[5]" = "1"
 			register "PcieClkSrcUsage[3]" = "5"
 			register "PcieClkSrcClkReq[3]" = "3"
-			register "PcieRpSlotImplemented[5]" = "1"
 		end
 		device pci 1c.6 off end # PCI Express Port 7
 		device pci 1c.7 on	# PCI Express Port 8