mb/intel/dcp847ske: remove reference to non-existent file

In commit 7a95204 (intel/dcp847ske: Add Intel NUC DCP847SKE)
the default_irq_route.asl file was removed, but this mainboard
was missed. Follow suit with the original intent of the commit
and fix the build breakage.

Change-Id: I909dad7cfc0fab37e29187b2358f7f056216a403
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/22975
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/intel/dcp847ske/dsdt.asl

@@ -37,7 +37,6 @@ DefinitionBlock(
 		#include <northbridge/intel/sandybridge/acpi/sandybridge.asl>
 		#include <drivers/intel/gma/acpi/default_brightness_levels.asl>
 		#include <southbridge/intel/bd82x6x/acpi/pch.asl>
-		#include <southbridge/intel/bd82x6x/acpi/default_irq_route.asl>
 		}
 	}
 }