i945 boards: Factor out MAX_CPUS

At least one mobile 945 series northbridge supports 4 threads, because
the dual-core Atom 330 CPU supports Hyper-threading. Therefore, we use
that as the default for this chipset.

Change-Id: I899ed1644d9b2da4fc72f09233a421200770110d
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41845
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/i945/Kconfig b/src/northbridge/intel/i945/Kconfig
index 754f36c..d6498f1 100644
--- a/src/northbridge/intel/i945/Kconfig
+++ b/src/northbridge/intel/i945/Kconfig
@@ -73,4 +73,8 @@
 	hex
 	default 0x100000
 
+config MAX_CPUS
+	int
+	default 4
+
 endif