f2fs: should not truncate blocks during roll-forward recovery

If the file preallocated blocks and fsync'ed, we should not truncate them during
roll-forward recovery which will recover i_size correctly back.

Fixes: d4dd19ec

 ("f2fs: do not expose unwritten blocks to user by DIO")
Cc: <stable@vger.kernel.org> # 5.17+
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>