[PATCH] cpu hotplug documentation fix

Looks like there was a merge conflict when patches
8f8b1138 and
255acee7 were applied which wasn't properly
resolved. Fix this and add some additional description.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>