[NET]: Shut up warnings in net/core/flow.c

Not really a network problem, more a !SMP issue.

net/core/flow.c:295: warning: statement with no effect

flow.c:295:        smp_call_function(flow_cache_flush_per_cpu, &info, 1, 0);

Fix this by converting the macro to an inline function, which
also increases the typechecking for !SMP builds.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/smp.h

@@ -94,7 +94,13 @@ void smp_prepare_boot_cpu(void);
  */
 #define raw_smp_processor_id()			0
 #define hard_smp_processor_id()			0
-#define smp_call_function(func,info,retry,wait)	({ 0; })
+
+static inline int smp_call_function(void (*func) (void *info), void *info,
+				    int retry, int wait)
+{
+	return 0;
+}
+
 #define on_each_cpu(func,info,retry,wait)	({ func(info); 0; })
 static inline void smp_send_reschedule(int cpu) { }
 #define num_booting_cpus()			1