soc/intel/cannonlake: Set MAX_CPUS based on the SoC and PCH

Set the default value for MAX_CPUS in the SoC config and drop it from
the mainboards where it is set to those values.

Change-Id: Ib56fdcfe770ef736a2c5e183481d9f9966570e6d
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52607
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/intel/cannonlake/Kconfig

@@ -119,7 +119,10 @@ config CPU_SPECIFIC_OPTIONS
 
 config MAX_CPUS
 	int
-	default 12
+	default 20 if SOC_INTEL_CANNONLAKE_PCH_H && SOC_INTEL_COMETLAKE
+	default 16 if SOC_INTEL_CANNONLAKE_PCH_H && SOC_INTEL_COFFEELAKE
+	default 12 if !SOC_INTEL_CANNONLAKE_PCH_H && SOC_INTEL_COMETLAKE
+	default 8
 
 config DIMM_SPD_SIZE
 	default 512