f2fs: compress: allow write compress released file after truncate to zero

For compressed file, after release compress blocks, don't allow write
direct, but we should allow write direct after truncate to zero.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Fengnan Chang <changfengnan@vivo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>