ec/google/chromeec: Configure EC_SYNC_IRQ as level triggered

EC_SYNC_IRQ from EC to host is level-triggered in practice and
configuring it as edge-triggered on the host results in host missing
events if there are multiple events queued on the EC side. This is
because Linux kernel driver reads one event per irq and the EC does
not de-assert the interrupt line until all events are drained
out. This results in event queue being filled up completely on the EC
and the host failing to see any of those events.

This change configures EC_SYNC_IRQ as level triggered to allow the
host to read events from the the EC as long as the line is asserted.

BUG=b:118949877

Change-Id: Id3fcfa0445f83865d57975a7bbc179dca047ba4c
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/29575
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Aseda Aboagye <aaboagye@google.com>

src/ec/google/chromeec/acpi/cros_ec.asl

@@ -25,7 +25,7 @@ Device (CREC)
 #ifdef EC_ENABLE_SYNC_IRQ
 	Name (_CRS, ResourceTemplate ()
 	{
-		Interrupt (ResourceConsumer, Edge, ActiveLow, Exclusive)
+		Interrupt (ResourceConsumer, Level, ActiveLow, Exclusive)
 		{
 			EC_SYNC_IRQ
 		}