google/chromeec: Ensure \_SB.LID0 is present before using it

Since we want to support devices that do not have a lid but still use
EC, we need to conditionally check if referencing \_SB.LID0 is valid.

BUG=b:35775024

Change-Id: I92433460ec870fb07f48e67a6dfc61e3c036a129
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/18941
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
diff --git a/src/ec/google/chromeec/acpi/ec.asl b/src/ec/google/chromeec/acpi/ec.asl
index a40d0ac..67cee27 100644
--- a/src/ec/google/chromeec/acpi/ec.asl
+++ b/src/ec/google/chromeec/acpi/ec.asl
@@ -26,6 +26,9 @@
 External (\_SB.DPTF.TCHG, DeviceObj)
 #endif
 External (\_SB.DPTF.TPET, MethodObj)
+#ifndef EC_ENABLE_LID_SWITCH
+External (\_SB.LID0, DeviceObj)
+#endif
 
 Device (EC0)
 {
@@ -169,7 +172,9 @@
 #ifdef EC_ENABLE_LID_SWITCH
 		Notify (LID0, 0x80)
 #else
-		Notify (\_SB.LID0, 0x80)
+		If (CondRefOf (\_SB.LID0)) {
+			Notify (\_SB.LID0, 0x80)
+		}
 #endif
 	}
 
@@ -181,7 +186,9 @@
 #ifdef EC_ENABLE_LID_SWITCH
 		Notify (LID0, 0x80)
 #else
-		Notify (\_SB.LID0, 0x80)
+		If (CondRefOf (\_SB.LID0)) {
+			Notify (\_SB.LID0, 0x80)
+		}
 #endif
 	}