mm: add memmap interface to reserved memory for mremap syscall useage

euleros inclusion
category: feature
feature: memmap

add memap interface to reserved memory for mremap syscall useage.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Jing xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>