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/51nb/x210/devicetree.cb b/src/mainboard/51nb/x210/devicetree.cb
index 1f2fa40..3ffc00f 100644
--- a/src/mainboard/51nb/x210/devicetree.cb
+++ b/src/mainboard/51nb/x210/devicetree.cb
@@ -39,8 +39,6 @@
 	register "PmConfigSlpSusMinAssert" = "3"	# 500ms
 	register "PmConfigSlpAMinAssert" = "3"		# 2s
 
-	register "serirq_mode" = "SERIRQ_CONTINUOUS"
-
 	# Enable Root Ports 3, 4 and 9
 	register "PcieRpEnable[2]" = "1" # Ethernet controller
 	register "PcieRpClkReqSupport[2]" = "1"
@@ -116,6 +114,8 @@
 		device ref pcie_rp4	on  end
 		device ref pcie_rp9	on  end
 		device ref lpc_espi	on
+			register "serirq_mode" = "SERIRQ_CONTINUOUS"
+
 			register "gen1_dec" = "0x000c0681"
 			register "gen2_dec" = "0x000c1641"