s390: increase CONFIG_NR_CPUS limit

In current models, maximum number of active cores is 101.

[heiko.carstens@de.ibm.com]: Xose's patch increased the maximum possible
value of CONFIG_NR_CPUS to 101. I changed this to 256 instead.
Signed-off-by: NXose Vazquez Perez <xose.vazquez@gmail.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -347,14 +347,14 @@ config SMP
 	  Even if you don't know what to do here, say Y.
 
 config NR_CPUS
-	int "Maximum number of CPUs (2-64)"
-	range 2 64
+	int "Maximum number of CPUs (2-256)"
+	range 2 256
 	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 64 and the
+	  kernel will support. The maximum supported value is 256 and the
 	  minimum value which makes sense is 2.
 
 	  This is purely to save memory - each supported CPU adds