mb/*: Remove lapic from devicetree

The parallel mp code picks up lapics at runtime, so remove it from all
devicetrees that use this codebase.

Change-Id: I5258a769c0f0ee4bbc4facc19737eed187b68c73
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69303
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/mainboard/system76/kbl-u/devicetree.cb

@@ -103,9 +103,7 @@ chip soc/intel/skylake
 		.dc_loadline = 310,
 	}"
 
-	device cpu_cluster 0 on
-		device lapic 0 on end
-	end
+	device cpu_cluster 0 on end
 
 	device domain 0 on
 		device ref system_agent on end