mm/damon/modules: deduplicate init steps for DAMON context setup

mainline inclusion
from mainline-v6.2-rc6
commit 7ae2c17f
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6MRUG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7ae2c17f53d5054d1fe5c1a103ad46068034617d

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DAMON_RECLAIM and DAMON_LRU_SORT has duplicated code for DAMON context and
target initializations.  Deduplicate the part by implementing a function
for the initialization in 'modules-common.c' and using it.

Link: https://lkml.kernel.org/r/20221026225943.100429-12-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ze Zuo <zuoze1@huawei.com>