mm/damon/core: initialize damo_filter->list from damos_new_filter()

In the Linux kernel, the following vulnerability has been resolved:

mm/damon/core: initialize damo_filter->list from damos_new_filter()

damos_new_filter() is not initializing the list field of newly allocated

filter object. However, DAMON sysfs interface and DAMON_RECLAIM are not

initializing it after calling damos_new_filter(). As a result, accessing

uninitialized memory is possible. Actually, adding multiple DAMOS filters

via DAMON sysfs interface caused NULL pointer dereferencing. Initialize

the field just after the allocation from damos_new_filter().