f2fs: remove wrong comment in f2fs_invalidate_page()

Since 8c242db9 ("f2fs: fix stale ATOMIC_WRITTEN_PAGE private pointer"),
we've started to not skip clear private flag for atomic_write page
truncation, so removing old wrong comment in f2fs_invalidate_page().
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -2711,7 +2711,6 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset,
 
 	clear_cold_data(page);
 
-	/* This is atomic written page, keep Private */
 	if (IS_ATOMIC_WRITTEN_PAGE(page))
 		return f2fs_drop_inmem_page(inode, page);