mb/starlabs/lite/{glk/glkr}: Configure prt0_gpio

PERST_0 is not used, so set this to GPIO_PRT0_UDEF (undefined) to
ensure that an undefined address is not added to GNVS.

Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Change-Id: Iac9b116b2fa28824a89db28911188364dc9a1a53
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64446
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@tutanota.com>
diff --git a/src/mainboard/starlabs/lite/variants/glk/devicetree.cb b/src/mainboard/starlabs/lite/variants/glk/devicetree.cb
index 287a64e..7bcad2a 100644
--- a/src/mainboard/starlabs/lite/variants/glk/devicetree.cb
+++ b/src/mainboard/starlabs/lite/variants/glk/devicetree.cb
@@ -29,6 +29,8 @@
 
 	register "ModPhyIfValue"		= "0x12"
 
+	register "prt0_gpio"			= "GPIO_PRT0_UDEF"
+
 	register "usb_config_override"		= "1"
 	register "DisableComplianceMode"	= "1"
 
diff --git a/src/mainboard/starlabs/lite/variants/glkr/devicetree.cb b/src/mainboard/starlabs/lite/variants/glkr/devicetree.cb
index 6eca34d..7bbeea7 100644
--- a/src/mainboard/starlabs/lite/variants/glkr/devicetree.cb
+++ b/src/mainboard/starlabs/lite/variants/glkr/devicetree.cb
@@ -29,6 +29,8 @@
 
 	register "ModPhyIfValue"		= "0x12"
 
+	register "prt0_gpio"			= "GPIO_PRT0_UDEF"
+
 	register "usb_config_override"		= "1"
 	register "DisableComplianceMode"	= "1"