soc/intel/tigerlake: Add enum for `DdiPortXConfig`

Add an enum for `DdiPortXConfig` devicetree options. Note that setting
these options to zero does not disable the corresponding DDI port, but
instead indicates that no LFP (Local Flat Panel, i.e. internal LCD) is
connected to it.

Change-Id: I9ea10141e51bf29ea44199dcd1b55b63ec771c0a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64047
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Tim Crawford <tcrawford@system76.com>
diff --git a/src/mainboard/intel/tglrvp/variants/tglrvp_up3/devicetree.cb b/src/mainboard/intel/tglrvp/variants/tglrvp_up3/devicetree.cb
index 2c9a548..1af05c4 100644
--- a/src/mainboard/intel/tglrvp/variants/tglrvp_up3/devicetree.cb
+++ b/src/mainboard/intel/tglrvp/variants/tglrvp_up3/devicetree.cb
@@ -68,7 +68,7 @@
 	register "SataPortsEnable[1]" = "1"
 
 	# enabling EDP in PortA
-	register "DdiPortAConfig" = "1"
+	register "DdiPortAConfig" = "DDI_PORT_CFG_EDP"
 
 	register "DdiPortBHpd" = "1"
 	register "DdiPort1Hpd" = "1"