skl mainboards/dt: Move serirq setting into LPC device scope

Change-Id: I84da5365907664ce223dec4adb22a8f1a6e2a144
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83188
Reviewed-by: Jonathon Hall <jonathon.hall@puri.sm>
Reviewed-by: Marvin Evers <marvin.n.evers@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <ericllai@google.com>
Reviewed-by: Erik van den Bogaert <ebogaert@eltan.com>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
diff --git a/src/mainboard/intel/saddlebrook/devicetree.cb b/src/mainboard/intel/saddlebrook/devicetree.cb
index 73df651..2f5058d 100644
--- a/src/mainboard/intel/saddlebrook/devicetree.cb
+++ b/src/mainboard/intel/saddlebrook/devicetree.cb
@@ -32,8 +32,6 @@
 	# SLP_A Minimum Assertion Width. Values 0: 0ms, 1: 4s, 2: 98ms, 3: 2s
 	register "PmConfigSlpAMinAssert" = "0x03"
 
-	register "serirq_mode" = "SERIRQ_CONTINUOUS"
-
 	# VR Settings Configuration for 4 Domains
 	#+----------------+-----------+-----------+-------------+----------+
 	#| Domain/Setting |     SA    |    IA     | GT Unsliced |    GT    |
@@ -217,6 +215,9 @@
 		device ref gspi1	on end
 		device ref hda		on end
 		device ref smbus	on end
+		device ref lpc_espi	on
+			register "serirq_mode" = "SERIRQ_CONTINUOUS"
+		end
 		device ref fast_spi	on end
 		device ref gbe		on end
 	end