CRIS: Fix missing NR_CPUS in menuconfig

The time Kconfig expects that NR_CPUS is defined.

This patch removes this config warning:
"kernel/time/Kconfig:163:warning: range is invalid"
Signed-off-by: NJesper Nilsson <jesper.nilsson@axis.com>

arch/cris/Kconfig

@@ -57,6 +57,10 @@ config HZ
 	int
 	default 100
 
+config NR_CPUS
+	int
+	default "1"
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"