In the beginning there is only one damos_action 'DAMOS_PAGEOUT' that need
to get the coldness score of a region for a scheme, which using
damon_pageout_score() to do that.  But now there are also other
damos_action actions need the coldness score, so rename it to
damon_cold_score() to make more sense.

Link: https://lkml.kernel.org/r/1663423014-28907-1-git-send-email-kaixuxia@tencent.comSigned-off-by: NKaixu Xia <kaixuxia@tencent.com>
Reviewed-by: NSeongJae Park <sj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>