smp: Provide 'setup_max_cpus' definition on UP too

This was already defined locally by init/main.c, but let's make
it generic, as arch/x86/kernel/cpu/topology.c is going to make
use of it to have more uniform code.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/smp.h

@@ -218,6 +218,8 @@ smp_call_function_any(const struct cpumask *mask, smp_call_func_t func,
 static inline void kick_all_cpus_sync(void) {  }
 static inline void wake_up_all_idle_cpus(void) {  }
 
+#define setup_max_cpus 0
+
 #ifdef CONFIG_UP_LATE_INIT
 extern void __init up_late_init(void);
 static inline void smp_init(void) { up_late_init(); }

init/main.c

@@ -603,7 +603,6 @@ static int __init rdinit_setup(char *str)
 __setup("rdinit=", rdinit_setup);
 
 #ifndef CONFIG_SMP
-static const unsigned int setup_max_cpus = NR_CPUS;
 static inline void setup_nr_cpu_ids(void) { }
 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
 #endif