The bodies of damon_{reclaim,lru_sort}_apply_parameters() contain
duplicates.  This commit adds a common function
damon_set_region_biggest_system_ram_default() to remove the duplicates.

Link: https://lkml.kernel.org/r/6329f00d.a70a0220.9bb29.3678SMTPIN_ADDED_BROKEN@mx.google.comSigned-off-by: NKaixu Xia <kaixuxia@tencent.com>
Suggested-by: NSeongJae Park <sj@kernel.org>
Reviewed-by: NSeongJae Park <sj@kernel.org>
Signed-off-by: NSeongJae Park <sj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>