tgl,adl,rpl mainboards: Drop superfluous cpu_cluster device

The cpu_cluster device is defined in the chipset devicetree. So drop it
from the mainboards.

Change-Id: Ib84e7804c03f1c0779ab7053a09e397a267a3844
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83523
Reviewed-by: Tim Crawford <tcrawford@system76.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/system76/adl/devicetree.cb

@@ -19,8 +19,6 @@ chip soc/intel/alderlake
 	# Thermal
 	register "tcc_offset" = "8"
 
-	device cpu_cluster 0 on end
-
 	device domain 0 on
 		device ref system_agent on end
 		device ref igpu on