asus/kfsn4-dre: Increase maximum logical CPUs for Istanbul devices

Test:
Single Opteron 2419 with 1GB RAM in slot A1
Booted Ubuntu Linux 14.04 and verified all 6 cores were visible
Brief stress test of all 6 cores simultaneously
Verified proper ACPI power states for all 6 cores

Change-Id: I1e598e36f9eaed5ba8a18b9c62ceedee16870f15
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: http://review.coreboot.org/8311
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
diff --git a/src/mainboard/asus/kfsn4-dre/Kconfig b/src/mainboard/asus/kfsn4-dre/Kconfig
index 245fecf..5779418 100644
--- a/src/mainboard/asus/kfsn4-dre/Kconfig
+++ b/src/mainboard/asus/kfsn4-dre/Kconfig
@@ -54,7 +54,7 @@
 
 config MAX_CPUS
 	int
-	default 8
+	default 12
 
 config MAX_PHYSICAL_CPUS
 	int