f2fs: remove redundant code from f2fs_write_begin

This code is being used for nobh_write_end() function.
But since now f2fs_write_end function is added so
there is no need for this code.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Pankaj Kumar <pankaj.km@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/data.c

@@ -634,9 +634,6 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 	int err = 0;
 	int ilock;
 
-	/* for nobh_write_end */
-	*fsdata = NULL;
-
 	f2fs_balance_fs(sbi);
 repeat:
 	page = grab_cache_page_write_begin(mapping, index, flags);