damon/sysfs: fix possible memleak on damon_sysfs_add_target

Bugzilla: https://bugzilla.redhat.com/2160210

commit 1c8e2349
Author: Levi Yun <ppbuk5246@gmail.com>
Date:   Mon Sep 26 16:06:11 2022 +0000

    damon/sysfs: fix possible memleak on damon_sysfs_add_target

    When damon_sysfs_add_target couldn't find proper task, New allocated
    damon_target structure isn't registered yet, So, it's impossible to free
    new allocated one by damon_sysfs_destroy_targets.

    By calling damon_add_target as soon as allocating new target, Fix this
    possible memory leak.

    Link: https://lkml.kernel.org/r/20220926160611.48536-1-sj@kernel.org


    Fixes: a61ea561 ("mm/damon/sysfs: link DAMON for virtual address spaces monitoring")
Signed-off-by: Levi Yun <ppbuk5246@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
    Cc: <stable@vger.kernel.org>    [5.17.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Chris von Recklinghausen <crecklin@redhat.com>