mm/memblock: reduce overhead in binary search

mm/memblock: reduce overhead in binary search

When checking that the indicated address belongs to the memory region, the
memory regions are checked one by one through a binary search, which will
be time consuming.

If the indicated address isn't in the memory region, then we needn't do
the time-consuming search.  Add a check on the indicated address for that
purpose.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>