mem-hotplug: let memblock skip the hotpluggable memory regions in __next_mem_range()

mem-hotplug: let memblock skip the hotpluggable memory regions in __next_mem_range()

Let memblock skip the hotpluggable memory regions in __next_mem_range(),
it is used to to prevent memblock from allocating hotpluggable memory
for the kernel at early time. The code is the same as __next_mem_range_rev().

Clear hotpluggable flag before releasing free pages to the buddy
allocator.  If we don't clear hotpluggable flag in
free_low_memory_core_early(), the memory which marked hotpluggable flag
will not free to buddy allocator.  Because __next_mem_range() will skip
them.

free_low_memory_core_early
	for_each_free_mem_range
		for_each_mem_range
			__next_mem_range

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>