notifiers: cpu: move cpu notifiers into cpu.h

We presently define all kinds of notifiers in notifier.h.  This is not
necessary at all, since different subsystems use different notifiers, they
are almost non-related with each other.

This can also save much build time.  Suppose I add a new netdevice event,
really I don't have to recompile all the source, just network related.
Without this patch, all the source will be recompiled.

I move the notify events near to their subsystem notifier registers, so
that they can be found more easily.

This patch:

It is not necessary to share the same notifier.h.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: David Miller <davem@davemloft.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>