f2fs: do not set LOST_PINO for newly created dir

Since directories will be written back with checkpoint and fsync a
directory will always write CP, there is no need to set LOST_PINO
after creating a directory.

Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>