f2fs: remove unneeded memory footprint accounting

We forgot to remov memory footprint accounting of per-cpu type
variables, fix it.

Fixes: 35782b23 ("f2fs: remove percpu_count due to performance regression")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>