f2fs: fix memleak of kobject

[ Upstream commit fe396ad8 ]

If kobject_init_and_add() failed, caller needs to invoke kobject_put()
to release kobject explicitly.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>