f2fs: remove duplicate code in f2fs_file_write_iter

We will do the same check in generic_write_checks.
if (iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)
        return -EINVAL;
just remove the same check in f2fs_file_write_iter.

Signed-off-by: Lihong Kou <koulihong@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -3160,11 +3160,6 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		goto out;
 	}
 
-	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT)) {
-		ret = -EINVAL;
-		goto out;
-	}
-
 	if (!inode_trylock(inode)) {
 		if (iocb->ki_flags & IOCB_NOWAIT) {
 			ret = -EAGAIN;