In lru_sort.c and reclaim.c, they are all defining get_monitoring_region()
function, there is no need to define it separately.

As 'get_monitoring_region()' is not a 'static' function anymore, we try to
use a prefix to distinguish with other functions, so there rename it to
'damon_find_biggest_system_ram'.

Link: https://lkml.kernel.org/r/20220909213606.136221-1-sj@kernel.orgSigned-off-by: NXin Hao <xhao@linux.alibaba.com>
Signed-off-by: NSeongJae Park <sj@kernel.org>
Suggested-by: NSeongJae Park <sj@kernel.org>
Reviewed-by: NSeongJae Park <sj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>