cpu: fix section mismatch warning in unregister_cpu_notifier

Fix following warning:
WARNING: vmlinux.o(.text+0x75f4e): Section mismatch in reference from the function unregister_cpu_notifier() to the variable .cpuinit.data:cpu_chain

We know that unregister_cpu_notifier is using HOTPLUG_CPU
stuff - so ignore these references.
Annotating unregister_cpu_notifier had been another option
but this caused far more warnings since not all callers were
annotated __cpuinit.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/cpu.c

@@ -149,7 +149,7 @@ int __cpuinit register_cpu_notifier(struct notifier_block *nb)
 
 EXPORT_SYMBOL(register_cpu_notifier);
 
-void unregister_cpu_notifier(struct notifier_block *nb)
+void __ref unregister_cpu_notifier(struct notifier_block *nb)
 {
 	cpu_maps_update_begin();
 	raw_notifier_chain_unregister(&cpu_chain, nb);