[ Upstream commit 67b0e42b768c9ddc3fd5ca1aee3db815cfaa635c ]

f2fs_ioc_gc_range skips blocks_per_seg each time, however, f2fs_gc moves
blocks of section each time, so fix it from segment to section.
Signed-off-by: NYunlong Song <yunlong.song@huawei.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>