cifs: return the more nuanced writeback error on close()

As filemap_check_errors() only report -EIO or -ENOSPC, we return more nuanced
writeback error -(file->f_mapping->wb_err & MAX_ERRNO).

  filemap_write_and_wait
    filemap_write_and_wait_range
      filemap_check_errors
        -ENOSPC or -EIO
  filemap_check_wb_err
    errseq_check
      return -(file->f_mapping->wb_err & MAX_ERRNO)

Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>