cpu hotplug: topology: remove topology_dev_map

By previous cpu hotplug notifier change, we don't need to track topology_dev
existence for each cpu by topology_dev_map.

Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>