mm/damon/sysfs: make kobj_type structures constant

Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.") the
driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definitions to prevent
modification at runtime.

Link: https://lkml.kernel.org/r/20230207-kobj_type-damon-v1-1-9d4fea6a465b@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/sysfs: move unsigned long range directory to common module

The implementation of unsigned long type range directories can be reused
by multiple DAMON sysfs directories including those for DAMON-based
Operation Schemes and the range of number of monitoring regions. Move the
code into the files for DAMON sysfs common logics.

Link: https://lkml.kernel.org/r/20221026225943.100429-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/sysfs: move sysfs_lock to common module

DAMON sysfs interface is implemented in a single file, sysfs.c, which has
about 2,800 lines of code. As the interface is hierarchical and some of
the code can be reused by different hierarchies, it would make more sense
to split out the implementation into common parts and different parts in
multiple files. As the beginning of the work, create files for common
code and move the global mutex for directories modifications protection
into the new file.

Link: https://lkml.kernel.org/r/20221026225943.100429-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>