Redefine {un}register_hotcpu_notifier() !HOTPLUG_CPU stubs

The return of the present "do {} while" based stub definition of
register_hotcpu_notifier() cannot be checked.  This makes the stub
asymmetric w.r.t.  the real HOTPLUG_CPU=y implementation that is
int-returning.  So let us redefine this to be consistent with the full
version.  Also do the same for unregister_hotcpu_notifier().

We cannot define these as static inline functions due to an existing GCC
bug (#33172).  So define as macros that return appropriately instead (int
'0' for the register_hotcpu_notifier case and void for
unregister_hotcpu_notifier).
Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/cpu.h

@@ -119,8 +119,9 @@ static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
 #define lock_cpu_hotplug()	do { } while (0)
 #define unlock_cpu_hotplug()	do { } while (0)
 #define hotcpu_notifier(fn, pri)	do { (void)(fn); } while (0)
-#define register_hotcpu_notifier(nb)	do { (void)(nb); } while (0)
-#define unregister_hotcpu_notifier(nb)	do { (void)(nb); } while (0)
+/* These aren't inline functions due to a GCC bug. */
+#define register_hotcpu_notifier(nb)	({ (void)(nb); 0; })
+#define unregister_hotcpu_notifier(nb)	({ (void)(nb); })
 
 /* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
 static inline int cpu_is_offline(int cpu) { return 0; }