s390/smp: increase maximum value of NR_CPUS to 512

With SMT we can have more than 256 CPUs. Let's make them available.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -373,14 +373,14 @@ config SMP
 	  Even if you don't know what to do here, say Y.
 
 config NR_CPUS
-	int "Maximum number of CPUs (2-256)"
-	range 2 256
+	int "Maximum number of CPUs (2-512)"
+	range 2 512
 	depends on SMP
 	default "32" if !64BIT
 	default "64" if 64BIT
 	help
 	  This allows you to specify the maximum number of CPUs which this
-	  kernel will support. The maximum supported value is 256 and the
+	  kernel will support. The maximum supported value is 512 and the
 	  minimum value which makes sense is 2.
 
 	  This is purely to save memory - each supported CPU adds