f2fs: include non-compressed blocks in compr_written_block

Need to include non-compressed blocks in compr_written_block to
estimate average compression ratio more accurately.

Fixes: 5ac443e2 ("f2fs: add sysfs nodes to get runtime compression stat")
Cc: stable@vger.kernel.org
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>