samples/damon/mtier: add parameters for node0 memory usage

Change the hard-coded quota goal metric values into sysfs knobs:
`node0_mem_used_bp` and `node0_mem_free_bp`.  These knobs represent the
used and free memory ratio of node0 in basis points (bp, where 1 bp =
0.01%).  As mentioned in [1], this patch is developed under the assumption
that node0 is always the fast-tier in a two-tiers memory setup.

[1] https://lore.kernel.org/linux-mm/20250420194030.75838-8-sj@kernel.org/

Link: https://lkml.kernel.org/r/20250627163329.50997-1-sj@kernel.org
Link: https://patch.msgid.link/20250619050313.1535-1-yunjeong.mun@sk.com


Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Suggested-by: Honggyu Kim <honggyu.kim@sk.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>